636897431 has 2 divisors, whose sum is σ = 636897432. Its totient is φ = 636897430.

The previous prime is 636897427. The next prime is 636897433. The reversal of 636897431 is 134798636.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 636897431 - 2² = 636897427 is a prime.

It is a super-2 number, since 2×636897431² = 811276675228799522, which contains 22 as substring.

Together with 636897433, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (636897433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318448715 + 318448716.

It is an arithmetic number, because the mean of its divisors is an integer number (318448716).

Almost surely, 2^636897431 is an apocalyptic number.

636897431 is a deficient number, since it is larger than the sum of its proper divisors (1).

636897431 is an equidigital number, since it uses as much as digits as its factorization.

636897431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 653184, while the sum is 47.

The square root of 636897431 is about 25236.8268805728. The cubic root of 636897431 is about 860.3790608584.

The spelling of 636897431 in words is "six hundred thirty-six million, eight hundred ninety-seven thousand, four hundred thirty-one".