21844421 has 4 divisors (see below), whose sum is σ = 21856992. Its totient is φ = 21831852.

The previous prime is 21844409. The next prime is 21844441. The reversal of 21844421 is 12444812.

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 21844421 - 2¹⁰ = 21843397 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 (21844441) 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, 3161 + ... + 7326.

It is an arithmetic number, because the mean of its divisors is an integer number (5464248).

Almost surely, 2^21844421 is an apocalyptic number.

It is an amenable number.

21844421 is a deficient number, since it is larger than the sum of its proper divisors (12571).

21844421 is a wasteful number, since it uses less digits than its factorization.

21844421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12570.

The product of its digits is 2048, while the sum is 26.

The square root of 21844421 is about 4673.8015576188. The cubic root of 21844421 is about 279.5418570766.

The spelling of 21844421 in words is "twenty-one million, eight hundred forty-four thousand, four hundred twenty-one".