644393832 has 32 divisors (see below), whose sum is σ = 1612121280. Its totient is φ = 214646400.

The previous prime is 644393791. The next prime is 644393879. The reversal of 644393832 is 238393446.

It is a super-5 number, since 5×644393832⁵ (a number of 45 digits) contains 55555 as substring.

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, 28332 + ... + 45732.

It is an arithmetic number, because the mean of its divisors is an integer number (50378790).

Almost surely, 2^644393832 is an apocalyptic number.

It is an amenable number.

644393832 is an abundant number, since it is smaller than the sum of its proper divisors (967727448).

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

644393832 is a wasteful number, since it uses less digits than its factorization.

644393832 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18953 (or 18949 counting only the distinct ones).

The product of its digits is 373248, while the sum is 42.

The square root of 644393832 is about 25384.9134723757. The cubic root of 644393832 is about 863.7415100360.

The spelling of 644393832 in words is "six hundred forty-four million, three hundred ninety-three thousand, eight hundred thirty-two".