644761602 has 24 divisors (see below), whose sum is σ = 1397829420. Its totient is φ = 214790400.

The previous prime is 644761597. The next prime is 644761603. The reversal of 644761602 is 206167446.

644761602 is a `hidden beast` number, since 6 + 4 + 47 + 6 + 1 + 602 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 642166281 + 2595321 = 25341^2 + 1611^2 .

It is not an unprimeable number, because it can be changed into a prime (644761603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22474 + ... + 42362.

Almost surely, 2^644761602 is an apocalyptic number.

644761602 is an abundant number, since it is smaller than the sum of its proper divisors (753067818).

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

644761602 is a wasteful number, since it uses less digits than its factorization.

644761602 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21698 (or 21695 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 36.

The square root of 644761602 is about 25392.1563085926. The cubic root of 644761602 is about 863.9057976641.

The spelling of 644761602 in words is "six hundred forty-four million, seven hundred sixty-one thousand, six hundred two".