21244121 has 2 divisors, whose sum is σ = 21244122. Its totient is φ = 21244120.

The previous prime is 21244073. The next prime is 21244163. The reversal of 21244121 is 12144212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16491721 + 4752400 = 4061^2 + 2180^2 .

It is a cyclic number.

It is not a de Polignac number, because 21244121 - 2²² = 17049817 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21244121.

It is not a weakly prime, because it can be changed into another prime (21244921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10622060 + 10622061.

It is an arithmetic number, because the mean of its divisors is an integer number (10622061).

Almost surely, 2^21244121 is an apocalyptic number.

It is an amenable number.

21244121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21244121 is an equidigital number, since it uses as much as digits as its factorization.

21244121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 128, while the sum is 17.

The square root of 21244121 is about 4609.1345174555. The cubic root of 21244121 is about 276.9573672262.

Adding to 21244121 its reverse (12144212), we get a palindrome (33388333).

Subtracting from 21244121 its reverse (12144212), we obtain a palindrome (9099909).

The spelling of 21244121 in words is "twenty-one million, two hundred forty-four thousand, one hundred twenty-one".