636400637 has 2 divisors, whose sum is σ = 636400638. Its totient is φ = 636400636.

The previous prime is 636400601. The next prime is 636400657. The reversal of 636400637 is 736004636.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 469112281 + 167288356 = 21659^2 + 12934^2 .

It is a cyclic number.

It is not a de Polignac number, because 636400637 - 2¹⁶ = 636335101 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 636400597 and 636400606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (636400657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318200318 + 318200319.

It is an arithmetic number, because the mean of its divisors is an integer number (318200319).

Almost surely, 2^636400637 is an apocalyptic number.

It is an amenable number.

636400637 is a deficient number, since it is larger than the sum of its proper divisors (1).

636400637 is an equidigital number, since it uses as much as digits as its factorization.

636400637 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54432, while the sum is 35.

The square root of 636400637 is about 25226.9823205234. The cubic root of 636400637 is about 860.1552978066.

The spelling of 636400637 in words is "six hundred thirty-six million, four hundred thousand, six hundred thirty-seven".