21924997 has 2 divisors, whose sum is σ = 21924998. Its totient is φ = 21924996.

The previous prime is 21924971. The next prime is 21925009. The reversal of 21924997 is 79942912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13549761 + 8375236 = 3681^2 + 2894^2 .

It is a cyclic number.

It is not a de Polignac number, because 21924997 - 2⁷ = 21924869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21924907) 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, 10962498 + 10962499.

It is an arithmetic number, because the mean of its divisors is an integer number (10962499).

Almost surely, 2^21924997 is an apocalyptic number.

It is an amenable number.

21924997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21924997 is an equidigital number, since it uses as much as digits as its factorization.

21924997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 43.

The square root of 21924997 is about 4682.4135870297. The cubic root of 21924997 is about 279.8851442192.

The spelling of 21924997 in words is "twenty-one million, nine hundred twenty-four thousand, nine hundred ninety-seven".