22000021 has 2 divisors, whose sum is σ = 22000022. Its totient is φ = 22000020.

The previous prime is 22000003. The next prime is 22000031. The reversal of 22000021 is 12000022.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17098225 + 4901796 = 4135^2 + 2214^2 .

It is a cyclic number.

It is not a de Polignac number, because 22000021 - 2¹⁹ = 21475733 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21999968 and 22000013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (22000001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11000010 + 11000011.

It is an arithmetic number, because the mean of its divisors is an integer number (11000011).

Almost surely, 2^22000021 is an apocalyptic number.

It is an amenable number.

22000021 is a deficient number, since it is larger than the sum of its proper divisors (1).

22000021 is an equidigital number, since it uses as much as digits as its factorization.

22000021 is an evil number, because the sum of its binary digits is even.

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

The square root of 22000021 is about 4690.4179984304. The cubic root of 22000021 is about 280.2040222213.

Adding to 22000021 its reverse (12000022), we get a palindrome (34000043).

Subtracting from 22000021 its reverse (12000022), we obtain a palindrome (9999999).

The spelling of 22000021 in words is "twenty-two million, twenty-one", and thus it is an aban number and an uban number.