21665166580954 has 32 divisors (see below), whose sum is σ = 35812055309184. Its totient is φ = 9766607054400.

The previous prime is 21665166580949. The next prime is 21665166580961. The reversal of 21665166580954 is 45908566156612.

It is a happy 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 15 ways as a sum of consecutive naturals, for example, 93855979 + ... + 94086529.

It is an arithmetic number, because the mean of its divisors is an integer number (1119126728412).

Almost surely, 2^{21665166580954} is an apocalyptic number.

21665166580954 is a deficient number, since it is larger than the sum of its proper divisors (14146888728230).

21665166580954 is a wasteful number, since it uses less digits than its factorization.

21665166580954 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314662.

The product of its (nonzero) digits is 93312000, while the sum is 64.

The spelling of 21665166580954 in words is "twenty-one trillion, six hundred sixty-five billion, one hundred sixty-six million, five hundred eighty thousand, nine hundred fifty-four".