644668000 has 48 divisors (see below), whose sum is σ = 1583959104. Its totient is φ = 257865600.

The previous prime is 644667979. The next prime is 644668021. The reversal of 644668000 is 866446.

It is an interprime number because it is at equal distance from previous prime (644667979) and next prime (644668021).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76584 + ... + 84583.

It is an arithmetic number, because the mean of its divisors is an integer number (32999148).

Almost surely, 2^644668000 is an apocalyptic number.

It is an amenable number.

644668000 is an abundant number, since it is smaller than the sum of its proper divisors (939291104).

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

644668000 is a wasteful number, since it uses less digits than its factorization.

644668000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161192 (or 161174 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 34.

The square root of 644668000 is about 25390.3131134691. The cubic root of 644668000 is about 863.8639903648.

The spelling of 644668000 in words is "six hundred forty-four million, six hundred sixty-eight thousand".