21556466361 has 24 divisors (see below), whose sum is σ = 33924580640. Its totient is φ = 13525621056.

The previous prime is 21556466329. The next prime is 21556466401. The reversal of 21556466361 is 16366465512.

21556466361 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 6 + 4 + 6 + 636 + 1 = 666.

It is not a de Polignac number, because 21556466361 - 2⁵ = 21556466329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21556466861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1373491 + ... + 1389096.

Almost surely, 2^21556466361 is an apocalyptic number.

It is an amenable number.

21556466361 is a deficient number, since it is larger than the sum of its proper divisors (12368114279).

21556466361 is a wasteful number, since it uses less digits than its factorization.

21556466361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2762630 (or 2762607 counting only the distinct ones).

The product of its digits is 777600, while the sum is 45.

The spelling of 21556466361 in words is "twenty-one billion, five hundred fifty-six million, four hundred sixty-six thousand, three hundred sixty-one".