261556664756562 has 96 divisors (see below), whose sum is σ = 655915515041280. Its totient is φ = 73778545077120.

The previous prime is 261556664756537. The next prime is 261556664756581. The reversal of 261556664756562 is 265657466655162.

261556664756562 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 122580888 + ... + 124696380.

It is an arithmetic number, because the mean of its divisors is an integer number (6832453281680).

Almost surely, 2^{261556664756562} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261556664756562, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (327957757520640).

261556664756562 is an abundant number, since it is smaller than the sum of its proper divisors (394358850284718).

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

261556664756562 is a wasteful number, since it uses less digits than its factorization.

261556664756562 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2128008 (or 2128005 counting only the distinct ones).

The product of its digits is 3265920000, while the sum is 72.

The spelling of 261556664756562 in words is "two hundred sixty-one trillion, five hundred fifty-six billion, six hundred sixty-four million, seven hundred fifty-six thousand, five hundred sixty-two".