644863032 has 80 divisors (see below), whose sum is σ = 1970436600. Its totient is φ = 195410880.

The previous prime is 644863019. The next prime is 644863033. The reversal of 644863032 is 230368446.

It is a happy number.

644863032 is a `hidden beast` number, since 644 + 8 + 6 + 3 + 0 + 3 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644863033) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 38107 + ... + 52362.

Almost surely, 2^644863032 is an apocalyptic number.

It is an amenable number.

644863032 is an abundant number, since it is smaller than the sum of its proper divisors (1325573568).

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

644863032 is a wasteful number, since it uses less digits than its factorization.

644863032 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90498 (or 90485 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 644863032 is about 25394.1535003630. The cubic root of 644863032 is about 863.9510967691.

The spelling of 644863032 in words is "six hundred forty-four million, eight hundred sixty-three thousand, thirty-two".