21667108818251 has 16 divisors (see below), whose sum is σ = 24574611899040. Its totient is φ = 18937952409600.

The previous prime is 21667108818221. The next prime is 21667108818253. The reversal of 21667108818251 is 15281880176612.

It is a cyclic number.

It is not a de Polignac number, because 21667108818251 - 2²⁶ = 21667041709387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21667108818253) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22212950 + ... + 23167851.

It is an arithmetic number, because the mean of its divisors is an integer number (1535913243690).

Almost surely, 2^{21667108818251} is an apocalyptic number.

21667108818251 is a deficient number, since it is larger than the sum of its proper divisors (2907503080789).

21667108818251 is a wasteful number, since it uses less digits than its factorization.

21667108818251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45382766.

The product of its (nonzero) digits is 2580480, while the sum is 56.

The spelling of 21667108818251 in words is "twenty-one trillion, six hundred sixty-seven billion, one hundred eight million, eight hundred eighteen thousand, two hundred fifty-one".