21621401716166 has 16 divisors (see below), whose sum is σ = 37066882106880. Its totient is φ = 9265909515720.

The previous prime is 21621401716157. The next prime is 21621401716177. The reversal of 21621401716166 is 66161710412612.

It is a super-3 number, since 3×21621401716166³ (a number of 41 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 33460670 + ... + 34100721.

It is an arithmetic number, because the mean of its divisors is an integer number (2316680131680).

Almost surely, 2^{21621401716166} is an apocalyptic number.

21621401716166 is a deficient number, since it is larger than the sum of its proper divisors (15445480390714).

21621401716166 is a wasteful number, since it uses less digits than its factorization.

21621401716166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67584259.

The product of its (nonzero) digits is 145152, while the sum is 44.

The spelling of 21621401716166 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred one million, seven hundred sixteen thousand, one hundred sixty-six".