21579791 has 2 divisors, whose sum is σ = 21579792. Its totient is φ = 21579790.

The previous prime is 21579737. The next prime is 21579793. The reversal of 21579791 is 19797512.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21579791 is a prime.

Together with 21579793, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21579793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10789895 + 10789896.

It is an arithmetic number, because the mean of its divisors is an integer number (10789896).

Almost surely, 2^21579791 is an apocalyptic number.

21579791 is a deficient number, since it is larger than the sum of its proper divisors (1).

21579791 is an equidigital number, since it uses as much as digits as its factorization.

21579791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 39690, while the sum is 41.

The square root of 21579791 is about 4645.4053644435. The cubic root of 21579791 is about 278.4084493337.

The spelling of 21579791 in words is "twenty-one million, five hundred seventy-nine thousand, seven hundred ninety-one".