21159791 has 2 divisors, whose sum is σ = 21159792. Its totient is φ = 21159790.

The previous prime is 21159779. The next prime is 21159811. The reversal of 21159791 is 19795112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21159791 - 2⁶ = 21159727 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21159751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10579895 + 10579896.

It is an arithmetic number, because the mean of its divisors is an integer number (10579896).

Almost surely, 2^21159791 is an apocalyptic number.

21159791 is a deficient number, since it is larger than the sum of its proper divisors (1).

21159791 is an equidigital number, since it uses as much as digits as its factorization.

21159791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5670, while the sum is 35.

The square root of 21159791 is about 4599.9772825526. The cubic root of 21159791 is about 276.5904141401.

The spelling of 21159791 in words is "twenty-one million, one hundred fifty-nine thousand, seven hundred ninety-one".