21310591 has 2 divisors, whose sum is σ = 21310592. Its totient is φ = 21310590.

The previous prime is 21310577. The next prime is 21310603. The reversal of 21310591 is 19501312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21310591 - 2¹¹ = 21308543 is a 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 (21310561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655295 + 10655296.

It is an arithmetic number, because the mean of its divisors is an integer number (10655296).

Almost surely, 2^21310591 is an apocalyptic number.

21310591 is a deficient number, since it is larger than the sum of its proper divisors (1).

21310591 is an equidigital number, since it uses as much as digits as its factorization.

21310591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 270, while the sum is 22.

The square root of 21310591 is about 4616.3395672329. The cubic root of 21310591 is about 277.2459206158.

The spelling of 21310591 in words is "twenty-one million, three hundred ten thousand, five hundred ninety-one".