21722919 has 4 divisors (see below), whose sum is σ = 28963896. Its totient is φ = 14481944.

The previous prime is 21722891. The next prime is 21722929. The reversal of 21722919 is 91922712.

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 21722919 - 2⁵ = 21722887 is a prime.

It is a super-2 number, since 2×21722919² = 943770419761122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21722919.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722929) 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, 3620484 + ... + 3620489.

It is an arithmetic number, because the mean of its divisors is an integer number (7240974).

Almost surely, 2^21722919 is an apocalyptic number.

21722919 is a deficient number, since it is larger than the sum of its proper divisors (7240977).

21722919 is an equidigital number, since it uses as much as digits as its factorization.

21722919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7240976.

The product of its digits is 4536, while the sum is 33.

The square root of 21722919 is about 4660.7852342712. The cubic root of 21722919 is about 279.0226083605.

The spelling of 21722919 in words is "twenty-one million, seven hundred twenty-two thousand, nine hundred nineteen".