261665131 has 16 divisors (see below), whose sum is σ = 339001600. Its totient is φ = 196134048.

The previous prime is 261665123. The next prime is 261665153. The reversal of 261665131 is 131566162.

It is a cyclic number.

It is not a de Polignac number, because 261665131 - 2³ = 261665123 is a prime.

It is a super-2 number, since 2×261665131² = 136937281562494322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 261665093 and 261665102.

It is not an unprimeable number, because it can be changed into a prime (261665101) 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, 73941 + ... + 77398.

It is an arithmetic number, because the mean of its divisors is an integer number (21187600).

Almost surely, 2^261665131 is an apocalyptic number.

261665131 is a deficient number, since it is larger than the sum of its proper divisors (77336469).

261665131 is a wasteful number, since it uses less digits than its factorization.

261665131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151378.

The product of its digits is 6480, while the sum is 31.

The square root of 261665131 is about 16176.0666108915. The cubic root of 261665131 is about 639.6100578727.

The spelling of 261665131 in words is "two hundred sixty-one million, six hundred sixty-five thousand, one hundred thirty-one".