644972519 has 2 divisors, whose sum is σ = 644972520. Its totient is φ = 644972518.

The previous prime is 644972467. The next prime is 644972563. The reversal of 644972519 is 915279446.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644972519 is a prime.

It is a super-2 number, since 2×644972519² = 831979100530410722, 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 (644972569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322486259 + 322486260.

It is an arithmetic number, because the mean of its divisors is an integer number (322486260).

Almost surely, 2^644972519 is an apocalyptic number.

644972519 is a deficient number, since it is larger than the sum of its proper divisors (1).

644972519 is an equidigital number, since it uses as much as digits as its factorization.

644972519 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 47.

The square root of 644972519 is about 25396.3091609785. The cubic root of 644972519 is about 863.9999888367. Note that the first 4 decimals are identical.

The spelling of 644972519 in words is "six hundred forty-four million, nine hundred seventy-two thousand, five hundred nineteen".