644275918224 has 45 divisors (see below), whose sum is σ = 1803104700033. Its totient is φ = 214755428736.

The previous prime is 644275918193. The next prime is 644275918241. The reversal of 644275918224 is 422819572446.

The square root of 644275918224 is 802668.

It is a perfect power (a square), and thus also a powerful number.

644275918224 is a `hidden beast` number, since 6 + 4 + 4 + 27 + 591 + 8 + 2 + 24 = 666.

It can be written as a sum of positive squares in only one way, i.e., 273248743824 + 371027174400 = 522732^2 + 609120^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 9598572 + ... + 9665460.

Almost surely, 2^644275918224 is an apocalyptic number.

644275918224 is the 802668-th square number.

It is an amenable number.

644275918224 is an abundant number, since it is smaller than the sum of its proper divisors (1158828781809).

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

644275918224 is an frugal number, since it uses more digits than its factorization.

644275918224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133792 (or 66894 counting only the distinct ones).

The product of its digits is 7741440, while the sum is 54.

The spelling of 644275918224 in words is "six hundred forty-four billion, two hundred seventy-five million, nine hundred eighteen thousand, two hundred twenty-four".