261553772162517 has 4 divisors (see below), whose sum is σ = 348738362883360. Its totient is φ = 174369181441676.

The previous prime is 261553772162497. The next prime is 261553772162591. The reversal of 261553772162517 is 715261277355162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 261553772162517 - 2⁶ = 261553772162453 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261553772166517) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43592295360417 + ... + 43592295360422.

It is an arithmetic number, because the mean of its divisors is an integer number (87184590720840).

Almost surely, 2^{261553772162517} is an apocalyptic number.

It is an amenable number.

261553772162517 is a deficient number, since it is larger than the sum of its proper divisors (87184590720843).

261553772162517 is an equidigital number, since it uses as much as digits as its factorization.

261553772162517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87184590720842.

The product of its digits is 37044000, while the sum is 60.

The spelling of 261553772162517 in words is "two hundred sixty-one trillion, five hundred fifty-three billion, seven hundred seventy-two million, one hundred sixty-two thousand, five hundred seventeen".