21666645064121 has 8 divisors (see below), whose sum is σ = 22252798478784. Its totient is φ = 21080521566000.

The previous prime is 21666645064081. The next prime is 21666645064133. The reversal of 21666645064121 is 12146054666612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21666645064121 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21666645064121.

It is not an unprimeable number, because it can be changed into a prime (21666645067121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6007205 + ... + 8911778.

It is an arithmetic number, because the mean of its divisors is an integer number (2781599809848).

Almost surely, 2^{21666645064121} is an apocalyptic number.

It is an amenable number.

21666645064121 is a deficient number, since it is larger than the sum of its proper divisors (586153414663).

21666645064121 is a wasteful number, since it uses less digits than its factorization.

21666645064121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14958271.

The product of its (nonzero) digits is 2488320, while the sum is 50.

The spelling of 21666645064121 in words is "twenty-one trillion, six hundred sixty-six billion, six hundred forty-five million, sixty-four thousand, one hundred twenty-one".