21719563 has 2 divisors, whose sum is σ = 21719564. Its totient is φ = 21719562.

The previous prime is 21719513. The next prime is 21719573. The reversal of 21719563 is 36591712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21719563 - 2⁹ = 21719051 is a prime.

It is not a weakly prime, because it can be changed into another prime (21719513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10859781 + 10859782.

It is an arithmetic number, because the mean of its divisors is an integer number (10859782).

Almost surely, 2^21719563 is an apocalyptic number.

21719563 is a deficient number, since it is larger than the sum of its proper divisors (1).

21719563 is an equidigital number, since it uses as much as digits as its factorization.

21719563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11340, while the sum is 34.

The square root of 21719563 is about 4660.4251951941. The cubic root of 21719563 is about 279.0082387739.

The spelling of 21719563 in words is "twenty-one million, seven hundred nineteen thousand, five hundred sixty-three".