21659719 has 2 divisors, whose sum is σ = 21659720. Its totient is φ = 21659718.

The previous prime is 21659711. The next prime is 21659741. The reversal of 21659719 is 91795612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21659719 - 2³ = 21659711 is a prime.

It is a super-2 number, since 2×21659719² = 938286854317922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21659711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10829859 + 10829860.

It is an arithmetic number, because the mean of its divisors is an integer number (10829860).

Almost surely, 2^21659719 is an apocalyptic number.

21659719 is a deficient number, since it is larger than the sum of its proper divisors (1).

21659719 is an equidigital number, since it uses as much as digits as its factorization.

21659719 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34020, while the sum is 40.

The square root of 21659719 is about 4654.0003223034. Note that the first 3 decimals coincide. The cubic root of 21659719 is about 278.7517522194.

The spelling of 21659719 in words is "twenty-one million, six hundred fifty-nine thousand, seven hundred nineteen".