21564299 has 2 divisors, whose sum is σ = 21564300. Its totient is φ = 21564298.

The previous prime is 21564289. The next prime is 21564307. The reversal of 21564299 is 99246512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21564299 is a prime.

It is a super-2 number, since 2×21564299² = 930037982722802, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21564239) 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, 10782149 + 10782150.

It is an arithmetic number, because the mean of its divisors is an integer number (10782150).

Almost surely, 2^21564299 is an apocalyptic number.

21564299 is a deficient number, since it is larger than the sum of its proper divisors (1).

21564299 is an equidigital number, since it uses as much as digits as its factorization.

21564299 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 38.

The square root of 21564299 is about 4643.7376110198. The cubic root of 21564299 is about 278.3418108103.

The spelling of 21564299 in words is "twenty-one million, five hundred sixty-four thousand, two hundred ninety-nine".