21133121 has 2 divisors, whose sum is σ = 21133122. Its totient is φ = 21133120.

The previous prime is 21133109. The next prime is 21133153. The reversal of 21133121 is 12133112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11122225 + 10010896 = 3335^2 + 3164^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21133121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21133096 and 21133105.

It is not a weakly prime, because it can be changed into another prime (21138121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10566560 + 10566561.

It is an arithmetic number, because the mean of its divisors is an integer number (10566561).

Almost surely, 2^21133121 is an apocalyptic number.

It is an amenable number.

21133121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21133121 is an equidigital number, since it uses as much as digits as its factorization.

21133121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36, while the sum is 14.

The square root of 21133121 is about 4597.0774411576. The cubic root of 21133121 is about 276.4741595621.

Adding to 21133121 its reverse (12133112), we get a palindrome (33266233).

Subtracting from 21133121 its reverse (12133112), we obtain a palindrome (9000009).

The spelling of 21133121 in words is "twenty-one million, one hundred thirty-three thousand, one hundred twenty-one".