644626880 has 28 divisors (see below), whose sum is σ = 1535018520. Its totient is φ = 257850624.

The previous prime is 644626867. The next prime is 644626883. The reversal of 644626880 is 88626446.

It is a super-3 number, since 3×644626880³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644626883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1006910 + ... + 1007549.

It is an arithmetic number, because the mean of its divisors is an integer number (54822090).

Almost surely, 2^644626880 is an apocalyptic number.

It is an amenable number.

644626880 is an abundant number, since it is smaller than the sum of its proper divisors (890391640).

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

644626880 is a wasteful number, since it uses less digits than its factorization.

644626880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2014476 (or 2014466 counting only the distinct ones).

The product of its (nonzero) digits is 442368, while the sum is 44.

The square root of 644626880 is about 25389.5033429171. The cubic root of 644626880 is about 863.8456228523.

The spelling of 644626880 in words is "six hundred forty-four million, six hundred twenty-six thousand, eight hundred eighty".