639887431 has 2 divisors, whose sum is σ = 639887432. Its totient is φ = 639887430.

The previous prime is 639887371. The next prime is 639887441. The reversal of 639887431 is 134788936.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639887431 is a prime.

It is a super-2 number, since 2×639887431² = 818911848703559522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639887441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319943715 + 319943716.

It is an arithmetic number, because the mean of its divisors is an integer number (319943716).

Almost surely, 2^639887431 is an apocalyptic number.

639887431 is a deficient number, since it is larger than the sum of its proper divisors (1).

639887431 is an equidigital number, since it uses as much as digits as its factorization.

639887431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 49.

The square root of 639887431 is about 25295.9963432951. The cubic root of 639887431 is about 861.7233475171.

The spelling of 639887431 in words is "six hundred thirty-nine million, eight hundred eighty-seven thousand, four hundred thirty-one".