261155562657 has 32 divisors (see below), whose sum is σ = 402291671040. Its totient is φ = 148934565120.

The previous prime is 261155562607. The next prime is 261155562667. The reversal of 261155562657 is 756265551162.

It is not a de Polignac number, because 261155562657 - 2⁶ = 261155562593 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is not an unprimeable number, because it can be changed into a prime (261155562607) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2780688 + ... + 2873070.

It is an arithmetic number, because the mean of its divisors is an integer number (12571614720).

Almost surely, 2^261155562657 is an apocalyptic number.

It is an amenable number.

261155562657 is a deficient number, since it is larger than the sum of its proper divisors (141136108383).

261155562657 is a wasteful number, since it uses less digits than its factorization.

261155562657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97453.

The product of its digits is 3780000, while the sum is 51.

The spelling of 261155562657 in words is "two hundred sixty-one billion, one hundred fifty-five million, five hundred sixty-two thousand, six hundred fifty-seven".