644564367 has 24 divisors (see below), whose sum is σ = 1008740304. Its totient is φ = 395023104.

The previous prime is 644564363. The next prime is 644564399. The reversal of 644564367 is 763465446.

It is a happy number.

It is not a de Polignac number, because 644564367 - 2² = 644564363 is a prime.

It is a super-2 number, since 2×644564367² = 830926446412221378, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644564363) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 42408 + ... + 55565.

It is an arithmetic number, because the mean of its divisors is an integer number (42030846).

Almost surely, 2^644564367 is an apocalyptic number.

644564367 is a deficient number, since it is larger than the sum of its proper divisors (364175937).

644564367 is a wasteful number, since it uses less digits than its factorization.

644564367 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98039 (or 98036 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 45.

The square root of 644564367 is about 25388.2722334546. The cubic root of 644564367 is about 863.8176980022.

The spelling of 644564367 in words is "six hundred forty-four million, five hundred sixty-four thousand, three hundred sixty-seven".