644805516 has 24 divisors (see below), whose sum is σ = 1510274304. Its totient is φ = 214116880.

The previous prime is 644805481. The next prime is 644805533. The reversal of 644805516 is 615508446.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99000 + ... + 105311.

It is an arithmetic number, because the mean of its divisors is an integer number (62928096).

Almost surely, 2^644805516 is an apocalyptic number.

It is an amenable number.

644805516 is an abundant number, since it is smaller than the sum of its proper divisors (865468788).

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

644805516 is a wasteful number, since it uses less digits than its factorization.

644805516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204581 (or 204579 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 39.

The square root of 644805516 is about 25393.0210097184. The cubic root of 644805516 is about 863.9254104418.

It can be divided in two parts, 64480 and 5516, that added together give a palindrome (69996).

The spelling of 644805516 in words is "six hundred forty-four million, eight hundred five thousand, five hundred sixteen".