261506631 has 16 divisors (see below), whose sum is σ = 369667584. Its totient is φ = 163868544.

The previous prime is 261506621. The next prime is 261506647. The reversal of 261506631 is 136605162.

It is not a de Polignac number, because 261506631 - 2⁷ = 261506503 is a prime.

It is a super-2 number, since 2×261506631² = 136771436113940322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261506621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42130 + ... + 47936.

It is an arithmetic number, because the mean of its divisors is an integer number (23104224).

Almost surely, 2^261506631 is an apocalyptic number.

261506631 is a deficient number, since it is larger than the sum of its proper divisors (108160953).

261506631 is a wasteful number, since it uses less digits than its factorization.

261506631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6710.

The product of its (nonzero) digits is 6480, while the sum is 30.

The square root of 261506631 is about 16171.1666555014. The cubic root of 261506631 is about 639.4808868337.

The spelling of 261506631 in words is "two hundred sixty-one million, five hundred six thousand, six hundred thirty-one".