644157016 has 8 divisors (see below), whose sum is σ = 1207794420. Its totient is φ = 322078504.

The previous prime is 644156983. The next prime is 644157049. The reversal of 644157016 is 610751446.

It is an interprime number because it is at equal distance from previous prime (644156983) and next prime (644157049).

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×644157016² = 829876522524048512, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 40259806 + ... + 40259821.

Almost surely, 2^644157016 is an apocalyptic number.

It is an amenable number.

644157016 is a deficient number, since it is larger than the sum of its proper divisors (563637404).

644157016 is a wasteful number, since it uses less digits than its factorization.

644157016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80519633 (or 80519629 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 644157016 is about 25380.2485409422. The cubic root of 644157016 is about 863.6356881707.

The spelling of 644157016 in words is "six hundred forty-four million, one hundred fifty-seven thousand, sixteen".