645943684 has 48 divisors (see below), whose sum is σ = 1272055680. Its totient is φ = 285500160.

The previous prime is 645943673. The next prime is 645943691. The reversal of 645943684 is 486349546.

It is a super-4 number, since 4×645943684⁴ (a number of 36 digits) contains 4444 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 67162 + ... + 76174.

It is an arithmetic number, because the mean of its divisors is an integer number (26501160).

Almost surely, 2^645943684 is an apocalyptic number.

It is an amenable number.

645943684 is a deficient number, since it is larger than the sum of its proper divisors (626111996).

645943684 is a wasteful number, since it uses less digits than its factorization.

645943684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9100 (or 9098 counting only the distinct ones).

The product of its digits is 2488320, while the sum is 49.

The square root of 645943684 is about 25415.4221684394. The cubic root of 645943684 is about 864.4334262964.

The spelling of 645943684 in words is "six hundred forty-five million, nine hundred forty-three thousand, six hundred eighty-four".