261657075256621 has 16 divisors (see below), whose sum is σ = 285586441079040. Its totient is φ = 237751448273920.

The previous prime is 261657075256613. The next prime is 261657075256639. The reversal of 261657075256621 is 126652570756162.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 261657075256621 - 2³ = 261657075256613 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261657075256621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261657075256321) 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, 437728881 + ... + 438326233.

It is an arithmetic number, because the mean of its divisors is an integer number (17849152567440).

Almost surely, 2^{261657075256621} is an apocalyptic number.

It is an amenable number.

261657075256621 is a deficient number, since it is larger than the sum of its proper divisors (23929365822419).

261657075256621 is a wasteful number, since it uses less digits than its factorization.

261657075256621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 617156.

The product of its (nonzero) digits is 63504000, while the sum is 61.

The spelling of 261657075256621 in words is "two hundred sixty-one trillion, six hundred fifty-seven billion, seventy-five million, two hundred fifty-six thousand, six hundred twenty-one".