644624613 has 6 divisors (see below), whose sum is σ = 931124454. Its totient is φ = 429749736.

The previous prime is 644624579. The next prime is 644624627. The reversal of 644624613 is 316426446.

644624613 is a `hidden beast` number, since 644 + 6 + 2 + 4 + 6 + 1 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 496710369 + 147914244 = 22287^2 + 12162^2 .

It is not a de Polignac number, because 644624613 - 2¹⁴ = 644608229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644624713) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35812470 + ... + 35812487.

It is an arithmetic number, because the mean of its divisors is an integer number (155187409).

Almost surely, 2^644624613 is an apocalyptic number.

It is an amenable number.

644624613 is a deficient number, since it is larger than the sum of its proper divisors (286499841).

644624613 is a wasteful number, since it uses less digits than its factorization.

644624613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71624963 (or 71624960 counting only the distinct ones).

The product of its digits is 82944, while the sum is 36.

The square root of 644624613 is about 25389.4586984441. The cubic root of 644624613 is about 863.8446102044.

The spelling of 644624613 in words is "six hundred forty-four million, six hundred twenty-four thousand, six hundred thirteen".