644424460 has 24 divisors (see below), whose sum is σ = 1354486896. Its totient is φ = 257542080.

The previous prime is 644424439. The next prime is 644424461. The reversal of 644424460 is 64424446.

It is not an unprimeable number, because it can be changed into a prime (644424461) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9979 + ... + 37261.

It is an arithmetic number, because the mean of its divisors is an integer number (56436954).

Almost surely, 2^644424460 is an apocalyptic number.

It is an amenable number.

644424460 is an abundant number, since it is smaller than the sum of its proper divisors (710062436).

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

644424460 is a wasteful number, since it uses less digits than its factorization.

644424460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28473 (or 28471 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 34.

The square root of 644424460 is about 25385.5167369112. The cubic root of 644424460 is about 863.7551943465.

It can be divided in two parts, 644 and 424460, that added together give a square (425104 = 652²).

The spelling of 644424460 in words is "six hundred forty-four million, four hundred twenty-four thousand, four hundred sixty".