644445460 has 48 divisors (see below), whose sum is σ = 1379653632. Its totient is φ = 252806400.

The previous prime is 644445443. The next prime is 644445479. The reversal of 644445460 is 64544446.

It is a super-2 number, since 2×644445460² = 830619901829223200, which contains 22 as substring.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 277705 + ... + 280015.

It is an arithmetic number, because the mean of its divisors is an integer number (28742784).

Almost surely, 2^644445460 is an apocalyptic number.

It is an amenable number.

644445460 is an abundant number, since it is smaller than the sum of its proper divisors (735208172).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644445460 is a wasteful number, since it uses less digits than its factorization.

644445460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2584 (or 2582 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 37.

The square root of 644445460 is about 25385.9303552184. The cubic root of 644445460 is about 863.7645767040.

The spelling of 644445460 in words is "six hundred forty-four million, four hundred forty-five thousand, four hundred sixty".