21642643441117 has 2 divisors, whose sum is σ = 21642643441118. Its totient is φ = 21642643441116.

The previous prime is 21642643441099. The next prime is 21642643441123. The reversal of 21642643441117 is 71114434624612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17729581843801 + 3913061597316 = 4210651^2 + 1978146^2 .

It is a cyclic number.

It is not a de Polignac number, because 21642643441117 - 2²³ = 21642635052509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21642643441217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821321720558 + 10821321720559.

It is an arithmetic number, because the mean of its divisors is an integer number (10821321720559).

Almost surely, 2^{21642643441117} is an apocalyptic number.

It is an amenable number.

21642643441117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642643441117 is an equidigital number, since it uses as much as digits as its factorization.

21642643441117 is an evil number, because the sum of its binary digits is even.

The product of its digits is 774144, while the sum is 46.

The spelling of 21642643441117 in words is "twenty-one trillion, six hundred forty-two billion, six hundred forty-three million, four hundred forty-one thousand, one hundred seventeen".