644427016 has 16 divisors (see below), whose sum is σ = 1223596800. Its totient is φ = 318134544.

The previous prime is 644426987. The next prime is 644427031. The reversal of 644427016 is 610724446.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 509200 + ... + 510463.

It is an arithmetic number, because the mean of its divisors is an integer number (76474800).

Almost surely, 2^644427016 is an apocalyptic number.

It is an amenable number.

644427016 is a deficient number, since it is larger than the sum of its proper divisors (579169784).

644427016 is a wasteful number, since it uses less digits than its factorization.

644427016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1019748 (or 1019744 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 34.

The square root of 644427016 is about 25385.5670805283. The cubic root of 644427016 is about 863.7563363243.

The spelling of 644427016 in words is "six hundred forty-four million, four hundred twenty-seven thousand, sixteen".