643678764 has 24 divisors (see below), whose sum is σ = 1502435760. Its totient is φ = 214485504.

The previous prime is 643678753. The next prime is 643678787. The reversal of 643678764 is 467876346.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35652 + ... + 50580.

It is an arithmetic number, because the mean of its divisors is an integer number (62601490).

Almost surely, 2^643678764 is an apocalyptic number.

It is an amenable number.

643678764 is an abundant number, since it is smaller than the sum of its proper divisors (858756996).

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

643678764 is a wasteful number, since it uses less digits than its factorization.

643678764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18529 (or 18527 counting only the distinct ones).

The product of its digits is 4064256, while the sum is 51.

The square root of 643678764 is about 25370.8250555633. The cubic root of 643678764 is about 863.4219008766.

It can be divided in two parts, 64 and 3678764, that added together give a triangular number (3678828 = T₂₇₁₂).

The spelling of 643678764 in words is "six hundred forty-three million, six hundred seventy-eight thousand, seven hundred sixty-four".