21719663 has 4 divisors (see below), whose sum is σ = 24822480. Its totient is φ = 18616848.

The previous prime is 21719657. The next prime is 21719683. The reversal of 21719663 is 36691712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21719663 - 2⁴ = 21719647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21719653) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1551398 + ... + 1551411.

It is an arithmetic number, because the mean of its divisors is an integer number (6205620).

Almost surely, 2^21719663 is an apocalyptic number.

21719663 is a deficient number, since it is larger than the sum of its proper divisors (3102817).

21719663 is an equidigital number, since it uses as much as digits as its factorization.

21719663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3102816.

The product of its digits is 13608, while the sum is 35.

The square root of 21719663 is about 4660.4359238166. The cubic root of 21719663 is about 279.0086669712.

The spelling of 21719663 in words is "twenty-one million, seven hundred nineteen thousand, six hundred sixty-three".