644506475 has 24 divisors (see below), whose sum is σ = 809948160. Its totient is φ = 508706720.

The previous prime is 644506459. The next prime is 644506487. The reversal of 644506475 is 574605446.

It is a happy number.

644506475 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644506475 - 2⁴ = 644506459 is a prime.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1281074 + ... + 1281576.

It is an arithmetic number, because the mean of its divisors is an integer number (33747840).

Almost surely, 2^644506475 is an apocalyptic number.

644506475 is a deficient number, since it is larger than the sum of its proper divisors (165441685).

644506475 is a wasteful number, since it uses less digits than its factorization.

644506475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1099 (or 1094 counting only the distinct ones).

The product of its (nonzero) digits is 403200, while the sum is 41.

The square root of 644506475 is about 25387.1320751281. The cubic root of 644506475 is about 863.7918357641.

The spelling of 644506475 in words is "six hundred forty-four million, five hundred six thousand, four hundred seventy-five".