261665574161331 has 32 divisors (see below), whose sum is σ = 349609904250880. Its totient is φ = 174082837975200.

The previous prime is 261665574161317. The next prime is 261665574161489. The reversal of 261665574161331 is 133161475566162.

It is not a de Polignac number, because 261665574161331 - 2⁶ = 261665574161267 is a prime.

It is a super-2 number, since 2×261665574161331² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34470497346 + ... + 34470504936.

It is an arithmetic number, because the mean of its divisors is an integer number (10925309507840).

Almost surely, 2^{261665574161331} is an apocalyptic number.

261665574161331 is a deficient number, since it is larger than the sum of its proper divisors (87944330089549).

261665574161331 is a wasteful number, since it uses less digits than its factorization.

261665574161331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16447.

The product of its digits is 16329600, while the sum is 57.

The spelling of 261665574161331 in words is "two hundred sixty-one trillion, six hundred sixty-five billion, five hundred seventy-four million, one hundred sixty-one thousand, three hundred thirty-one".