21666353652164 has 24 divisors (see below), whose sum is σ = 40833135983808. Its totient is φ = 9999759394080.

The previous prime is 21666353652157. The next prime is 21666353652179. The reversal of 21666353652164 is 46125635366612.

It is a super-2 number, since 2×21666353652164² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3607649 + ... + 7506519.

It is an arithmetic number, because the mean of its divisors is an integer number (1701380665992).

Almost surely, 2^{21666353652164} is an apocalyptic number.

It is an amenable number.

21666353652164 is a deficient number, since it is larger than the sum of its proper divisors (19166782331644).

21666353652164 is a wasteful number, since it uses less digits than its factorization.

21666353652164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4005755 (or 4005753 counting only the distinct ones).

The product of its digits is 27993600, while the sum is 56.

The spelling of 21666353652164 in words is "twenty-one trillion, six hundred sixty-six billion, three hundred fifty-three million, six hundred fifty-two thousand, one hundred sixty-four".