261564210617551 has 8 divisors (see below), whose sum is σ = 271942987088304. Its totient is φ = 251375870412480.

The previous prime is 261564210617513. The next prime is 261564210617617. The reversal of 261564210617551 is 155716012465162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261564210617551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261564216617551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 47609063620 + ... + 47609069113.

It is an arithmetic number, because the mean of its divisors is an integer number (33992873386038).

Almost surely, 2^{261564210617551} is an apocalyptic number.

261564210617551 is a deficient number, since it is larger than the sum of its proper divisors (10378776470753).

261564210617551 is an equidigital number, since it uses as much as digits as its factorization.

261564210617551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95218132841.

The product of its (nonzero) digits is 3024000, while the sum is 52.

The spelling of 261564210617551 in words is "two hundred sixty-one trillion, five hundred sixty-four billion, two hundred ten million, six hundred seventeen thousand, five hundred fifty-one".