644815152 has 30 divisors (see below), whose sum is σ = 1804587252. Its totient is φ = 214938336.

The previous prime is 644815133. The next prime is 644815181. The reversal of 644815152 is 251518446.

It is a happy number.

644815152 is a `hidden beast` number, since 64 + 4 + 81 + 515 + 2 = 666.

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

It is a zygodrome in base 3.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2238798 + ... + 2239085.

Almost surely, 2^644815152 is an apocalyptic number.

It is an amenable number.

644815152 is an abundant number, since it is smaller than the sum of its proper divisors (1159772100).

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

644815152 is a wasteful number, since it uses less digits than its factorization.

644815152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4477897 (or 4477888 counting only the distinct ones).

The product of its digits is 38400, while the sum is 36.

The square root of 644815152 is about 25393.2107461817. The cubic root of 644815152 is about 863.9297139326.

The spelling of 644815152 in words is "six hundred forty-four million, eight hundred fifteen thousand, one hundred fifty-two".