261325664 has 24 divisors (see below), whose sum is σ = 515063808. Its totient is φ = 130515840.

The previous prime is 261325657. The next prime is 261325679. The reversal of 261325664 is 466523162.

It is a happy number.

It is a super-2 number, since 2×261325664² = 136582205330081792, which contains 22 as substring.

It is a congruent number.

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, 27809 + ... + 35999.

It is an arithmetic number, because the mean of its divisors is an integer number (21460992).

Almost surely, 2^261325664 is an apocalyptic number.

It is an amenable number.

261325664 is a deficient number, since it is larger than the sum of its proper divisors (253738144).

261325664 is an equidigital number, since it uses as much as digits as its factorization.

261325664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9198 (or 9190 counting only the distinct ones).

The product of its digits is 51840, while the sum is 35.

The square root of 261325664 is about 16165.5703270871. The cubic root of 261325664 is about 639.3333422736. Note that the first 4 decimals are identical.

The spelling of 261325664 in words is "two hundred sixty-one million, three hundred twenty-five thousand, six hundred sixty-four".