644572242 has 20 divisors (see below), whose sum is σ = 1444319646. Its totient is φ = 214857360.

The previous prime is 644572237. The next prime is 644572303. The reversal of 644572242 is 242275446.

644572242 is a `hidden beast` number, since 6 + 44 + 572 + 2 + 42 = 666.

It can be written as a sum of positive squares in only one way, i.e., 447703281 + 196868961 = 21159^2 + 14031^2 .

It is a junction number, because it is equal to n+sod(n) for n = 644572197 and 644572206.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1989259 + ... + 1989582.

Almost surely, 2^644572242 is an apocalyptic number.

644572242 is an abundant number, since it is smaller than the sum of its proper divisors (799747404).

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

644572242 is a wasteful number, since it uses less digits than its factorization.

644572242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3978855 (or 3978846 counting only the distinct ones).

The product of its digits is 107520, while the sum is 36.

The square root of 644572242 is about 25388.4273242751. The cubic root of 644572242 is about 863.8212159010.

It can be divided in two parts, 6445 and 72242, that added together give a palindrome (78687).

The spelling of 644572242 in words is "six hundred forty-four million, five hundred seventy-two thousand, two hundred forty-two".