261388864 has 28 divisors (see below), whose sum is σ = 565849008. Its totient is φ = 118812800.

The previous prime is 261388849. The next prime is 261388877. The reversal of 261388864 is 468883162.

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, 184942 + ... + 186349.

Almost surely, 2^261388864 is an apocalyptic number.

It is an amenable number.

261388864 is an abundant number, since it is smaller than the sum of its proper divisors (304460144).

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

261388864 is a wasteful number, since it uses less digits than its factorization.

261388864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371314 (or 371304 counting only the distinct ones).

The product of its digits is 442368, while the sum is 46.

The square root of 261388864 is about 16167.5249806518. The cubic root of 261388864 is about 639.3848777278.

The spelling of 261388864 in words is "two hundred sixty-one million, three hundred eighty-eight thousand, eight hundred sixty-four".