21526723168721 has 2 divisors, whose sum is σ = 21526723168722. Its totient is φ = 21526723168720.

The previous prime is 21526723168679. The next prime is 21526723168739. The reversal of 21526723168721 is 12786132762512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20463762168721 + 1062961000000 = 4523689^2 + 1031000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21526723168721 is a prime.

It is not a weakly prime, because it can be changed into another prime (21526723168771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10763361584360 + 10763361584361.

It is an arithmetic number, because the mean of its divisors is an integer number (10763361584361).

Almost surely, 2^{21526723168721} is an apocalyptic number.

It is an amenable number.

21526723168721 is a deficient number, since it is larger than the sum of its proper divisors (1).

21526723168721 is an equidigital number, since it uses as much as digits as its factorization.

21526723168721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3386880, while the sum is 53.

The spelling of 21526723168721 in words is "twenty-one trillion, five hundred twenty-six billion, seven hundred twenty-three million, one hundred sixty-eight thousand, seven hundred twenty-one".