636644131 has 2 divisors, whose sum is σ = 636644132. Its totient is φ = 636644130.

The previous prime is 636644087. The next prime is 636644143. The reversal of 636644131 is 131446636.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 636644131 - 2¹³ = 636635939 is a prime.

It is a super-3 number, since 3×636644131³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (636644231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318322065 + 318322066.

It is an arithmetic number, because the mean of its divisors is an integer number (318322066).

Almost surely, 2^636644131 is an apocalyptic number.

636644131 is a deficient number, since it is larger than the sum of its proper divisors (1).

636644131 is an equidigital number, since it uses as much as digits as its factorization.

636644131 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 34.

The square root of 636644131 is about 25231.8079217483. The cubic root of 636644131 is about 860.2649854970.

The spelling of 636644131 in words is "six hundred thirty-six million, six hundred forty-four thousand, one hundred thirty-one".