21723541291 has 2 divisors, whose sum is σ = 21723541292. Its totient is φ = 21723541290.

The previous prime is 21723541249. The next prime is 21723541303. The reversal of 21723541291 is 19214532712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21723541291 - 2²⁵ = 21689986859 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21723541291.

It is not a weakly prime, because it can be changed into another prime (21723541211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10861770645 + 10861770646.

It is an arithmetic number, because the mean of its divisors is an integer number (10861770646).

Almost surely, 2^21723541291 is an apocalyptic number.

21723541291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21723541291 is an equidigital number, since it uses as much as digits as its factorization.

21723541291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 37.

The spelling of 21723541291 in words is "twenty-one billion, seven hundred twenty-three million, five hundred forty-one thousand, two hundred ninety-one".