644217672 has 64 divisors (see below), whose sum is σ = 1920660480. Its totient is φ = 176058432.

The previous prime is 644217653. The next prime is 644217713. The reversal of 644217672 is 276712446.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 644217672.

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, 79498 + ... + 87225.

It is an arithmetic number, because the mean of its divisors is an integer number (30010320).

Almost surely, 2^644217672 is an apocalyptic number.

It is an amenable number.

644217672 is an abundant number, since it is smaller than the sum of its proper divisors (1276442808).

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

644217672 is a wasteful number, since it uses less digits than its factorization.

644217672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166762 (or 166758 counting only the distinct ones).

The product of its digits is 112896, while the sum is 39.

The square root of 644217672 is about 25381.4434577705. The cubic root of 644217672 is about 863.6627949376.

The spelling of 644217672 in words is "six hundred forty-four million, two hundred seventeen thousand, six hundred seventy-two".