261564210617553 has 6 divisors (see below), whose sum is σ = 377814970892034. Its totient is φ = 174376140411696.

The previous prime is 261564210617513. The next prime is 261564210617617. The reversal of 261564210617553 is 355716012465162.

261564210617553 is a `hidden beast` number, since 2 + 6 + 1 + 5 + 6 + 4 + 2 + 10 + 617 + 5 + 5 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 249766036704144 + 11798173913409 = 15803988^2 + 3434847^2 .

It is not a de Polignac number, because 261564210617553 - 2¹² = 261564210613457 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261564210617553.

It is not an unprimeable number, because it can be changed into a prime (261564210617513) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14531345034300 + ... + 14531345034317.

It is an arithmetic number, because the mean of its divisors is an integer number (62969161815339).

Almost surely, 2^{261564210617553} is an apocalyptic number.

It is an amenable number.

261564210617553 is a deficient number, since it is larger than the sum of its proper divisors (116250760274481).

261564210617553 is a wasteful number, since it uses less digits than its factorization.

261564210617553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29062690068623 (or 29062690068620 counting only the distinct ones).

The product of its (nonzero) digits is 9072000, while the sum is 54.

The spelling of 261564210617553 in words is "two hundred sixty-one trillion, five hundred sixty-four billion, two hundred ten million, six hundred seventeen thousand, five hundred fifty-three".