21022451 has 2 divisors, whose sum is σ = 21022452. Its totient is φ = 21022450.

The previous prime is 21022447. The next prime is 21022459. The reversal of 21022451 is 15422012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21022451 - 2² = 21022447 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21022459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511225 + 10511226.

It is an arithmetic number, because the mean of its divisors is an integer number (10511226).

Almost surely, 2^21022451 is an apocalyptic number.

21022451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21022451 is an equidigital number, since it uses as much as digits as its factorization.

21022451 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21022451 is about 4585.0246455172. The cubic root of 21022451 is about 275.9907010450.

Adding to 21022451 its reverse (15422012), we get a palindrome (36444463).

The spelling of 21022451 in words is "twenty-one million, twenty-two thousand, four hundred fifty-one".