21646555525161 has 96 divisors (see below), whose sum is σ = 37342949529600. Its totient is φ = 12071532132576.

The previous prime is 21646555525157. The next prime is 21646555525163. The reversal of 21646555525161 is 16152555564612.

21646555525161 is a `hidden beast` number, since 2 + 1 + 6 + 4 + 6 + 5 + 55 + 525 + 1 + 61 = 666.

It is not a de Polignac number, because 21646555525161 - 2² = 21646555525157 is a prime.

It is a super-2 number, since 2×21646555525161² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21646555525098 and 21646555525107.

It is not an unprimeable number, because it can be changed into a prime (21646555525163) by changing a digit.

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 95 ways as a sum of consecutive naturals, for example, 157494876 + ... + 157632258.

It is an arithmetic number, because the mean of its divisors is an integer number (388989057600).

Almost surely, 2^{21646555525161} is an apocalyptic number.

21646555525161 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21646555525161 is a deficient number, since it is larger than the sum of its proper divisors (15696394004439).

21646555525161 is a wasteful number, since it uses less digits than its factorization.

21646555525161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138640 (or 138623 counting only the distinct ones).

The product of its digits is 10800000, while the sum is 54.

The spelling of 21646555525161 in words is "twenty-one trillion, six hundred forty-six billion, five hundred fifty-five million, five hundred twenty-five thousand, one hundred sixty-one".