21399307 has 2 divisors, whose sum is σ = 21399308. Its totient is φ = 21399306.

The previous prime is 21399299. The next prime is 21399319. The reversal of 21399307 is 70399312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21399307 - 2³ = 21399299 is a prime.

It is not a weakly prime, because it can be changed into another prime (21399907) 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, 10699653 + 10699654.

It is an arithmetic number, because the mean of its divisors is an integer number (10699654).

Almost surely, 2^21399307 is an apocalyptic number.

21399307 is a deficient number, since it is larger than the sum of its proper divisors (1).

21399307 is an equidigital number, since it uses as much as digits as its factorization.

21399307 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10206, while the sum is 34.

The square root of 21399307 is about 4625.9384993750. The cubic root of 21399307 is about 277.6301129414.

The spelling of 21399307 in words is "twenty-one million, three hundred ninety-nine thousand, three hundred seven".