21104591 has 2 divisors, whose sum is σ = 21104592. Its totient is φ = 21104590.

The previous prime is 21104569. The next prime is 21104641. The reversal of 21104591 is 19540112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21104591 - 2⁶ = 21104527 is a prime.

It is a super-2 number, since 2×21104591² = 890807522554562, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21104561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10552295 + 10552296.

It is an arithmetic number, because the mean of its divisors is an integer number (10552296).

Almost surely, 2^21104591 is an apocalyptic number.

21104591 is a deficient number, since it is larger than the sum of its proper divisors (1).

21104591 is an equidigital number, since it uses as much as digits as its factorization.

21104591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 21104591 is about 4593.9733347071. The cubic root of 21104591 is about 276.3496889111.

The spelling of 21104591 in words is "twenty-one million, one hundred four thousand, five hundred ninety-one".