21451121 has 2 divisors, whose sum is σ = 21451122. Its totient is φ = 21451120.

The previous prime is 21451103. The next prime is 21451139. The reversal of 21451121 is 12115412.

It is a balanced prime because it is at equal distance from previous prime (21451103) and next prime (21451139).

It can be written as a sum of positive squares in only one way, i.e., 20976400 + 474721 = 4580^2 + 689^2 .

It is a cyclic number.

It is not a de Polignac number, because 21451121 - 2¹⁸ = 21188977 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21451121.

It is not a weakly prime, because it can be changed into another prime (21451141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10725560 + 10725561.

It is an arithmetic number, because the mean of its divisors is an integer number (10725561).

Almost surely, 2^21451121 is an apocalyptic number.

It is an amenable number.

21451121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21451121 is an equidigital number, since it uses as much as digits as its factorization.

21451121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80, while the sum is 17.

The square root of 21451121 is about 4631.5354905258. The cubic root of 21451121 is about 277.8540069841.

Adding to 21451121 its reverse (12115412), we get a palindrome (33566533).

The spelling of 21451121 in words is "twenty-one million, four hundred fifty-one thousand, one hundred twenty-one".