21719959 has 2 divisors, whose sum is σ = 21719960. Its totient is φ = 21719958.

The previous prime is 21719953. The next prime is 21719989. The reversal of 21719959 is 95991712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21719959 - 2¹⁵ = 21687191 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21719953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10859979 + 10859980.

It is an arithmetic number, because the mean of its divisors is an integer number (10859980).

Almost surely, 2^21719959 is an apocalyptic number.

21719959 is a deficient number, since it is larger than the sum of its proper divisors (1).

21719959 is an equidigital number, since it uses as much as digits as its factorization.

21719959 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51030, while the sum is 43.

The square root of 21719959 is about 4660.4676803943. The cubic root of 21719959 is about 279.0099344278.

The spelling of 21719959 in words is "twenty-one million, seven hundred nineteen thousand, nine hundred fifty-nine".