# Basic Mathematical Special Constants Table

Symbol Value Name
0 = 0 Zero
1 = 1 One, Unity
i = –1 Imaginary unit, unit imaginary number
π ≈ 3.14159 26535 89793 23846 26433 83279 50288 Pi, Archimedes' constant or Ludolph's number
e ≈ 2.71828 18284 59045 23536 02874 71352 66249 e, Napier's constant, or Euler's number
2 ≈ 1.41421 35623 73095 04880 16887 24209 69807 Pythagoras' constant, square root of 2
3 ≈ 1.73205 08075 68877 29352 74463 41505 87236 Theodorus' constant, square root of 3
5 ≈ 2.23606 79774 99789 69640 91736 68731 27623 square root of 5
γ ≈ 0.57721 56649 01532 86060 65120 90082 40243 Euler–Mascheroni constant
≈ 1.61803 39887 49894 84820 45868 34365 63811 Golden ratio
Λ ≥ –1.1 · 10−12 de Bruijn–Newman constant
M1 ≈ 0.26149 72128 47642 78375 54268 38608 69585 Meissel–Mertens constant
β ≈ 0.28016 94990 23869 13303 Bernstein's constant
λ ≈ 0.30366 30028 98732 65859 74481 21901 55623 Gauss–Kuzmin–Wirsing constant
σ ≈ 0.35323 63718 54995 98454 35165 50432 68201 Hafner–Sarnak–McCurley constant
L ≈ 0.5 Landau's constant
Ω ≈ 0.56714 32904 09783 87299 99686 62210 35554 Omega constant
λ , μ ≈ 0.62432 99885 43550 87099 29363 83100 83724 Golomb–Dickman constant
≈ 0.64341 05462 Cahen's constant
C2 ≈ 0.66016 18158 46869 57392 78121 10014 55577 Twin prime constant
≈ 0.66274 34193 49181 58097 47420 97109 25290 Laplace limit
β ≈ 0.70258 Embree–Trefethen constant
K ≈ 0.76422 36535 89220 66299 06987 31250 09232 Landau–Ramanujan constant
B4 ≈ 0.87058 838 Brun's constant for prime quadruplets
K ≈ 0.91596 55941 77219 01505 46035 14932 38411 Catalan's constant
L = 1 Legendre's constant
Λ ≈ 1.09868 58055 Lengyel's constant
K ≈ 1.13198 824 Viswanath's constant
ζ ≈ 1.20205 69031 59594 28539 97381 61511 44999 Apéry's constant
λ ≈ 1.30357 72690 34296 39125 70991 12152 55189 Conway's constant
θ ≈ 1.30637 78838 63080 69046 86144 92602 60571 Mills' constant
ρ ≈ 1.32471 79572 44746 02596 09088 54478 09734 Plastic constant
μ ≈ 1.45136 92348 83381 05028 39684 85892 02744 Ramanujan–Soldner constant
≈ 1.45607 49485 82689 67139 95953 51116 54356 Backhouse's constant
≈ 1.46707 80794 Porter's constant
≈ 1.53960 07178 Lieb's square ice constant
EB ≈ 1.60669 51524 15291 76378 33015 23190 92458 Erdos–Borwein constant
≈ 1.70521 11401 05367 76428 85514 53434 50816 Niven's constant
B2 ≈ 1.90216 05831 04 Brun's constant for twin primes
P2 ≈ 2.29558 71493 92638 07403 42980 49189 49039 Universal parabolic constant
α ≈ 2.50290 78750 95892 82228 39028 73218 21578 Feigenbaum constant
K ≈ 2.58498 17595 79253 21706 58935 87383 17116 Sierpinski's constant
≈ 2.68545 20010 65306 44530 97148 35481 79569 Khinchin's constant
F ≈ 2.80777 02420 28519 36522 15011 86557 77293 Fransén–Robinson constant
≈ 3.27582 29187 21811 15978 76818 82453 84386 Lévy's constant
ψ ≈ 3.35988 56662 43177 55317 20113 02918 92717 Reciprocal Fibonacci constant
δ ≈ 4.66920 16091 02990 67185 32038 20466 20161 Feigenbaum constant