21926021 has 16 divisors (see below), whose sum is σ = 24987648. Its totient is φ = 19094400.

The previous prime is 21926011. The next prime is 21926033. The reversal of 21926021 is 12062912.

It is not a de Polignac number, because 21926021 - 2¹⁰ = 21924997 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 (21926011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15860 + ... + 17186.

It is an arithmetic number, because the mean of its divisors is an integer number (1561728).

Almost surely, 2^21926021 is an apocalyptic number.

It is an amenable number.

21926021 is a deficient number, since it is larger than the sum of its proper divisors (3061627).

21926021 is a wasteful number, since it uses less digits than its factorization.

21926021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1412.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21926021 is about 4682.5229310704. The cubic root of 21926021 is about 279.8895014669.

Adding to 21926021 its reverse (12062912), we get a palindrome (33988933).

The spelling of 21926021 in words is "twenty-one million, nine hundred twenty-six thousand, twenty-one".