261532665 has 32 divisors (see below), whose sum is σ = 475770240. Its totient is φ = 136237248.

The previous prime is 261532657. The next prime is 261532673. The reversal of 261532665 is 566235162.

It is a happy number.

261532665 is a `hidden beast` number, since 2 + 61 + 532 + 6 + 65 = 666.

It is an interprime number because it is at equal distance from previous prime (261532657) and next prime (261532673).

It is not a de Polignac number, because 261532665 - 2³ = 261532657 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16722 + ... + 28331.

It is an arithmetic number, because the mean of its divisors is an integer number (14867820).

Almost surely, 2^261532665 is an apocalyptic number.

It is an amenable number.

261532665 is a deficient number, since it is larger than the sum of its proper divisors (214237575).

261532665 is a wasteful number, since it uses less digits than its factorization.

261532665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45110 (or 45104 counting only the distinct ones).

The product of its digits is 64800, while the sum is 36.

The square root of 261532665 is about 16171.9715866681. The cubic root of 261532665 is about 639.5021070642.

The spelling of 261532665 in words is "two hundred sixty-one million, five hundred thirty-two thousand, six hundred sixty-five".