21725579 has 2 divisors, whose sum is σ = 21725580. Its totient is φ = 21725578.

The previous prime is 21725573. The next prime is 21725581. The reversal of 21725579 is 97552712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21725579 - 2²⁰ = 20677003 is a prime.

It is a Sophie Germain prime.

Together with 21725581, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21725573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10862789 + 10862790.

It is an arithmetic number, because the mean of its divisors is an integer number (10862790).

Almost surely, 2^21725579 is an apocalyptic number.

21725579 is a deficient number, since it is larger than the sum of its proper divisors (1).

21725579 is an equidigital number, since it uses as much as digits as its factorization.

21725579 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 44100, while the sum is 38.

The square root of 21725579 is about 4661.0705851768. The cubic root of 21725579 is about 279.0339967908.

The spelling of 21725579 in words is "twenty-one million, seven hundred twenty-five thousand, five hundred seventy-nine".