644641572 has 48 divisors (see below), whose sum is σ = 1530183872. Its totient is φ = 211178880.

The previous prime is 644641561. The next prime is 644641583. The reversal of 644641572 is 275146446.

It is an interprime number because it is at equal distance from previous prime (644641561) and next prime (644641583).

It is a self number, because there is not a number n which added to its sum of digits gives 644641572.

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, 530838 + ... + 532050.

Almost surely, 2^644641572 is an apocalyptic number.

It is an amenable number.

644641572 is an abundant number, since it is smaller than the sum of its proper divisors (885542300).

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

644641572 is a wasteful number, since it uses less digits than its factorization.

644641572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1948 (or 1946 counting only the distinct ones).

The product of its digits is 161280, while the sum is 39.

The square root of 644641572 is about 25389.7926734347. The cubic root of 644641572 is about 863.8521855756.

The spelling of 644641572 in words is "six hundred forty-four million, six hundred forty-one thousand, five hundred seventy-two".