21666566566612 has 48 divisors (see below), whose sum is σ = 42326246172672. Its totient is φ = 9619210349280.

The previous prime is 21666566566607. The next prime is 21666566566639.

21666566566612 is nontrivially palindromic in base 10.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 133545213 + ... + 133707355.

It is an arithmetic number, because the mean of its divisors is an integer number (881796795264).

Almost surely, 2^{21666566566612} is an apocalyptic number.

21666566566612 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21666566566612 is a deficient number, since it is larger than the sum of its proper divisors (20659679606060).

21666566566612 is a wasteful number, since it uses less digits than its factorization.

21666566566612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232828 (or 232826 counting only the distinct ones).

The product of its digits is 167961600, while the sum is 64.

The spelling of 21666566566612 in words is "twenty-one trillion, six hundred sixty-six billion, five hundred sixty-six million, five hundred sixty-six thousand, six hundred twelve".