261553311331665 has 8 divisors (see below), whose sum is σ = 418485298130688. Its totient is φ = 139495099376880.

The previous prime is 261553311331651. The next prime is 261553311331673. The reversal of 261553311331665 is 566133113355162.

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

It is not a de Polignac number, because 261553311331665 - 2⁶ = 261553311331601 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8718443711041 + ... + 8718443711070.

It is an arithmetic number, because the mean of its divisors is an integer number (52310662266336).

Almost surely, 2^{261553311331665} is an apocalyptic number.

It is an amenable number.

261553311331665 is a deficient number, since it is larger than the sum of its proper divisors (156931986799023).

261553311331665 is a wasteful number, since it uses less digits than its factorization.

261553311331665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17436887422119.

The product of its digits is 4374000, while the sum is 51.

The spelling of 261553311331665 in words is "two hundred sixty-one trillion, five hundred fifty-three billion, three hundred eleven million, three hundred thirty-one thousand, six hundred sixty-five".