21552451 has 2 divisors, whose sum is σ = 21552452. Its totient is φ = 21552450.

The previous prime is 21552437. The next prime is 21552457. The reversal of 21552451 is 15425512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21552451 - 2¹⁵ = 21519683 is a prime.

It is not a weakly prime, because it can be changed into another prime (21552457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776225 + 10776226.

It is an arithmetic number, because the mean of its divisors is an integer number (10776226).

Almost surely, 2^21552451 is an apocalyptic number.

21552451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21552451 is an equidigital number, since it uses as much as digits as its factorization.

21552451 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2000, while the sum is 25.

The square root of 21552451 is about 4642.4617392069. The cubic root of 21552451 is about 278.2908253377.

Adding to 21552451 its reverse (15425512), we get a palindrome (36977963).

The spelling of 21552451 in words is "twenty-one million, five hundred fifty-two thousand, four hundred fifty-one".