21661056132465 has 16 divisors (see below), whose sum is σ = 35852782564800. Its totient is φ = 11154199019712.

The previous prime is 21661056132437. The next prime is 21661056132503. The reversal of 21661056132465 is 56423165016612.

It is a happy number.

It is not a de Polignac number, because 21661056132465 - 2⁷ = 21661056132337 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24897765235 + ... + 24897766104.

It is an arithmetic number, because the mean of its divisors is an integer number (2240798910300).

Almost surely, 2^{21661056132465} is an apocalyptic number.

It is an amenable number.

21661056132465 is a deficient number, since it is larger than the sum of its proper divisors (14191726432335).

21661056132465 is a wasteful number, since it uses less digits than its factorization.

21661056132465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49795531376.

The product of its (nonzero) digits is 1555200, while the sum is 48.

The spelling of 21661056132465 in words is "twenty-one trillion, six hundred sixty-one billion, fifty-six million, one hundred thirty-two thousand, four hundred sixty-five".