21722541 has 4 divisors (see below), whose sum is σ = 28963392. Its totient is φ = 14481692.

The previous prime is 21722531. The next prime is 21722543. The reversal of 21722541 is 14522712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21722541 - 2⁵ = 21722509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722543) 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, 3620421 + ... + 3620426.

It is an arithmetic number, because the mean of its divisors is an integer number (7240848).

Almost surely, 2^21722541 is an apocalyptic number.

It is an amenable number.

21722541 is a deficient number, since it is larger than the sum of its proper divisors (7240851).

21722541 is an equidigital number, since it uses as much as digits as its factorization.

21722541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7240850.

The product of its digits is 1120, while the sum is 24.

The square root of 21722541 is about 4660.7446829879. The cubic root of 21722541 is about 279.0209899292.

The spelling of 21722541 in words is "twenty-one million, seven hundred twenty-two thousand, five hundred forty-one".