261564915 has 16 divisors (see below), whose sum is σ = 428237568. Its totient is φ = 136256736.

The previous prime is 261564893. The next prime is 261564929. The reversal of 261564915 is 519465162.

It is not a de Polignac number, because 261564915 - 2⁵ = 261564883 is a prime.

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, 202119 + ... + 203408.

It is an arithmetic number, because the mean of its divisors is an integer number (26764848).

Almost surely, 2^261564915 is an apocalyptic number.

261564915 is a deficient number, since it is larger than the sum of its proper divisors (166672653).

261564915 is a wasteful number, since it uses less digits than its factorization.

261564915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405578.

The product of its digits is 64800, while the sum is 39.

The square root of 261564915 is about 16172.9686514257. The cubic root of 261564915 is about 639.5283919839.

The spelling of 261564915 in words is "two hundred sixty-one million, five hundred sixty-four thousand, nine hundred fifteen".