644209676 has 24 divisors (see below), whose sum is σ = 1232400960. Its totient is φ = 292216400.

The previous prime is 644209673. The next prime is 644209693. The reversal of 644209676 is 676902446.

It is a super-2 number, since 2×644209676² = 830012213304049952, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is not an unprimeable number, because it can be changed into a prime (644209673) 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, 6695 + ... + 36513.

It is an arithmetic number, because the mean of its divisors is an integer number (51350040).

Almost surely, 2^644209676 is an apocalyptic number.

It is an amenable number.

644209676 is a deficient number, since it is larger than the sum of its proper divisors (588191284).

644209676 is a wasteful number, since it uses less digits than its factorization.

644209676 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30325 (or 30323 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 44.

The square root of 644209676 is about 25381.2859406296. The cubic root of 644209676 is about 863.6592216752.

The spelling of 644209676 in words is "six hundred forty-four million, two hundred nine thousand, six hundred seventy-six".