21718583 has 2 divisors, whose sum is σ = 21718584. Its totient is φ = 21718582.

The previous prime is 21718553. The next prime is 21718597. The reversal of 21718583 is 38581712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21718583 - 2⁸ = 21718327 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 (21718513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10859291 + 10859292.

It is an arithmetic number, because the mean of its divisors is an integer number (10859292).

Almost surely, 2^21718583 is an apocalyptic number.

21718583 is a deficient number, since it is larger than the sum of its proper divisors (1).

21718583 is an equidigital number, since it uses as much as digits as its factorization.

21718583 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13440, while the sum is 35.

The square root of 21718583 is about 4660.3200533869. The cubic root of 21718583 is about 279.0040423698.

The spelling of 21718583 in words is "twenty-one million, seven hundred eighteen thousand, five hundred eighty-three".