261646077761631 has 16 divisors (see below), whose sum is σ = 387653675685120. Its totient is φ = 174417282957240.

The previous prime is 261646077761617. The next prime is 261646077761633. The reversal of 261646077761631 is 136167770646162.

261646077761631 is a `hidden beast` number, since 2 + 6 + 1 + 6 + 4 + 6 + 0 + 7 + 7 + 7 + 616 + 3 + 1 = 666.

It is not a de Polignac number, because 261646077761631 - 2⁷ = 261646077761503 is a prime.

It is a super-2 number, since 2×261646077761631² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261646077761633) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 372852705 + ... + 373553786.

It is an arithmetic number, because the mean of its divisors is an integer number (24228354730320).

Almost surely, 2^{261646077761631} is an apocalyptic number.

261646077761631 is a deficient number, since it is larger than the sum of its proper divisors (126007597923489).

261646077761631 is a wasteful number, since it uses less digits than its factorization.

261646077761631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 746419483 (or 746419477 counting only the distinct ones).

The product of its (nonzero) digits is 64012032, while the sum is 63.

The spelling of 261646077761631 in words is "two hundred sixty-one trillion, six hundred forty-six billion, seventy-seven million, seven hundred sixty-one thousand, six hundred thirty-one".