261287565217 has 8 divisors (see below), whose sum is σ = 298757872512. Its totient is φ = 223853136000.

The previous prime is 261287565197. The next prime is 261287565251. The reversal of 261287565217 is 712565782162.

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-261287565217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261287535217) 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, 8953909 + ... + 8983042.

It is an arithmetic number, because the mean of its divisors is an integer number (37344734064).

Almost surely, 2^261287565217 is an apocalyptic number.

It is an amenable number.

261287565217 is a deficient number, since it is larger than the sum of its proper divisors (37470307295).

261287565217 is a wasteful number, since it uses less digits than its factorization.

261287565217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17939039.

The product of its digits is 2822400, while the sum is 52.

The spelling of 261287565217 in words is "two hundred sixty-one billion, two hundred eighty-seven million, five hundred sixty-five thousand, two hundred seventeen".