643897976 has 16 divisors (see below), whose sum is σ = 1239939240. Its totient is φ = 313247520.

The previous prime is 643897921. The next prime is 643898027. The reversal of 643897976 is 679798346.

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 in 3 ways as a sum of consecutive naturals, for example, 1087370 + ... + 1087961.

Almost surely, 2^643897976 is an apocalyptic number.

It is an amenable number.

643897976 is a deficient number, since it is larger than the sum of its proper divisors (596041264).

643897976 is a wasteful number, since it uses less digits than its factorization.

643897976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2175374 (or 2175370 counting only the distinct ones).

The product of its digits is 13716864, while the sum is 59.

The square root of 643897976 is about 25375.1448468772. The cubic root of 643897976 is about 863.5199057460.

The spelling of 643897976 in words is "six hundred forty-three million, eight hundred ninety-seven thousand, nine hundred seventy-six".