644952631 has 2 divisors, whose sum is σ = 644952632. Its totient is φ = 644952630.

The previous prime is 644952599. The next prime is 644952677. The reversal of 644952631 is 136259446.

644952631 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644952631 - 2⁵ = 644952599 is a prime.

It is a super-2 number, since 2×644952631² = 831927792467644322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644952031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322476315 + 322476316.

It is an arithmetic number, because the mean of its divisors is an integer number (322476316).

Almost surely, 2^644952631 is an apocalyptic number.

644952631 is a deficient number, since it is larger than the sum of its proper divisors (1).

644952631 is an equidigital number, since it uses as much as digits as its factorization.

644952631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 155520, while the sum is 40.

The square root of 644952631 is about 25395.9176050010. The cubic root of 644952631 is about 863.9911081439.

The spelling of 644952631 in words is "six hundred forty-four million, nine hundred fifty-two thousand, six hundred thirty-one".