261281518155 has 192 divisors, whose sum is σ = 556091827200. Its totient is φ = 115206727680.

The previous prime is 261281518123. The next prime is 261281518159. The reversal of 261281518155 is 551815182162.

261281518155 is a `hidden beast` number, since 2 + 6 + 1 + 2 + 81 + 518 + 1 + 55 = 666.

It is not a de Polignac number, because 261281518155 - 2⁵ = 261281518123 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 261281518155.

It is not an unprimeable number, because it can be changed into a prime (261281518159) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 31030536 + ... + 31038954.

It is an arithmetic number, because the mean of its divisors is an integer number (2896311600).

Almost surely, 2^261281518155 is an apocalyptic number.

261281518155 is an abundant number, since it is smaller than the sum of its proper divisors (294810309045).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261281518155 is an equidigital number, since it uses as much as digits as its factorization.

261281518155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8576 (or 8564 counting only the distinct ones).

The product of its digits is 192000, while the sum is 45.

The spelling of 261281518155 in words is "two hundred sixty-one billion, two hundred eighty-one million, five hundred eighteen thousand, one hundred fifty-five".