21331451 has 2 divisors, whose sum is σ = 21331452. Its totient is φ = 21331450.

The previous prime is 21331399. The next prime is 21331459. The reversal of 21331451 is 15413312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21331451 - 2¹⁴ = 21315067 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21331459) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10665725 + 10665726.

It is an arithmetic number, because the mean of its divisors is an integer number (10665726).

Almost surely, 2^21331451 is an apocalyptic number.

21331451 is the 2066-th centered decagonal number.

21331451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21331451 is an equidigital number, since it uses as much as digits as its factorization.

21331451 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 360, while the sum is 20.

The square root of 21331451 is about 4618.5983804613. The cubic root of 21331451 is about 277.3363523938.

Adding to 21331451 its reverse (15413312), we get a palindrome (36744763).

The spelling of 21331451 in words is "twenty-one million, three hundred thirty-one thousand, four hundred fifty-one".