22021 has 6 divisors (see below), whose sum is σ = 23622. Its totient is φ = 20520.

The previous prime is 22013. The next prime is 22027. The reversal of 22021 is 12022.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 12996 + 9025 = 114^2 + 95^2 .

It is not a de Polignac number, because 22021 - 2³ = 22013 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21995 and 22013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22027) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 331 + ... + 391.

It is an arithmetic number, because the mean of its divisors is an integer number (3937).

2²²⁰²¹ is an apocalyptic number.

It is an amenable number.

22021 is a deficient number, since it is larger than the sum of its proper divisors (1601).

22021 is an equidigital number, since it uses as much as digits as its factorization.

22021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99 (or 80 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 7.

The square root of 22021 is about 148.3947438422. The cubic root of 22021 is about 28.0293060510.

Adding to 22021 its reverse (12022), we get a palindrome (34043).

Subtracting from 22021 its reverse (12022), we obtain a palindrome (9999).

The spelling of 22021 in words is "twenty-two thousand, twenty-one", and thus it is an iban number.