644965902431 has 2 divisors, whose sum is σ = 644965902432. Its totient is φ = 644965902430.

The previous prime is 644965902397. The next prime is 644965902437. The reversal of 644965902431 is 134209569446.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644965902431 is a prime.

It is a super-2 number, since 2×644965902431² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644965902437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322482951215 + 322482951216.

It is an arithmetic number, because the mean of its divisors is an integer number (322482951216).

Almost surely, 2^644965902431 is an apocalyptic number.

644965902431 is a deficient number, since it is larger than the sum of its proper divisors (1).

644965902431 is an equidigital number, since it uses as much as digits as its factorization.

644965902431 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5598720, while the sum is 53.

The spelling of 644965902431 in words is "six hundred forty-four billion, nine hundred sixty-five million, nine hundred two thousand, four hundred thirty-one".