644254016 has 28 divisors (see below), whose sum is σ = 1461077088. Its totient is φ = 276108672.

The previous prime is 644254003. The next prime is 644254057. The reversal of 644254016 is 610452446.

It is a tau number, because it is divible by the number of its divisors (28).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 718586 + ... + 719481.

Almost surely, 2^644254016 is an apocalyptic number.

It is an amenable number.

644254016 is an abundant number, since it is smaller than the sum of its proper divisors (816823072).

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

644254016 is a wasteful number, since it uses less digits than its factorization.

644254016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1438086 (or 1438076 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 32.

The square root of 644254016 is about 25382.1594038017. The cubic root of 644254016 is about 863.6790360166.

The spelling of 644254016 in words is "six hundred forty-four million, two hundred fifty-four thousand, sixteen".