643864264 has 16 divisors (see below), whose sum is σ = 1248875100. Its totient is φ = 310830912.

The previous prime is 643864259. The next prime is 643864279. The reversal of 643864264 is 462468346.

It can be written as a sum of positive squares in 2 ways, for example, as 593312164 + 50552100 = 24358^2 + 7110^2 .

It is a super-2 number, since 2×643864264² = 829122380912523392, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 643864264.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1387407 + ... + 1387870.

Almost surely, 2^643864264 is an apocalyptic number.

It is an amenable number.

643864264 is a deficient number, since it is larger than the sum of its proper divisors (605010836).

643864264 is a wasteful number, since it uses less digits than its factorization.

643864264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2775312 (or 2775308 counting only the distinct ones).

The product of its digits is 663552, while the sum is 43.

The square root of 643864264 is about 25374.4805661121. The cubic root of 643864264 is about 863.5048352989.

The spelling of 643864264 in words is "six hundred forty-three million, eight hundred sixty-four thousand, two hundred sixty-four".