21299807 has 2 divisors, whose sum is σ = 21299808. Its totient is φ = 21299806.

The previous prime is 21299791. The next prime is 21299809. The reversal of 21299807 is 70899212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21299807 - 2⁴ = 21299791 is a prime.

Together with 21299809, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21299809) 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, 10649903 + 10649904.

It is an arithmetic number, because the mean of its divisors is an integer number (10649904).

Almost surely, 2^21299807 is an apocalyptic number.

21299807 is a deficient number, since it is larger than the sum of its proper divisors (1).

21299807 is an equidigital number, since it uses as much as digits as its factorization.

21299807 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 21299807 is about 4615.1713944338. The cubic root of 21299807 is about 277.1991469330.

The spelling of 21299807 in words is "twenty-one million, two hundred ninety-nine thousand, eight hundred seven".