21144121 has 2 divisors, whose sum is σ = 21144122. Its totient is φ = 21144120.

The previous prime is 21144119. The next prime is 21144173. The reversal of 21144121 is 12144112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19009600 + 2134521 = 4360^2 + 1461^2 .

It is a cyclic number.

It is not a de Polignac number, because 21144121 - 2¹ = 21144119 is a prime.

Together with 21144119, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21144095 and 21144104.

It is not a weakly prime, because it can be changed into another prime (21144181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572060 + 10572061.

It is an arithmetic number, because the mean of its divisors is an integer number (10572061).

Almost surely, 2^21144121 is an apocalyptic number.

It is an amenable number.

21144121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144121 is an equidigital number, since it uses as much as digits as its factorization.

21144121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64, while the sum is 16.

The square root of 21144121 is about 4598.2736978131. The cubic root of 21144121 is about 276.5221204264.

Adding to 21144121 its reverse (12144112), we get a palindrome (33288233).

Subtracting from 21144121 its reverse (12144112), we obtain a palindrome (9000009).

The spelling of 21144121 in words is "twenty-one million, one hundred forty-four thousand, one hundred twenty-one".