644846080 has 40 divisors (see below), whose sum is σ = 1546125372. Its totient is φ = 257937408.

The previous prime is 644846051. The next prime is 644846087. The reversal of 644846080 is 80648446.

It can be written as a sum of positive squares in 2 ways, for example, as 644753664 + 92416 = 25392^2 + 304^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (644846087) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123387 + ... + 128506.

Almost surely, 2^644846080 is an apocalyptic number.

It is an amenable number.

644846080 is an abundant number, since it is smaller than the sum of its proper divisors (901279292).

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

644846080 is an equidigital number, since it uses as much as digits as its factorization.

644846080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251916 (or 251900 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 40.

The square root of 644846080 is about 25393.8197205541. The cubic root of 644846080 is about 863.9435262585.

The spelling of 644846080 in words is "six hundred forty-four million, eight hundred forty-six thousand, eighty".