21015299 has 2 divisors, whose sum is σ = 21015300. Its totient is φ = 21015298.

The previous prime is 21015289. The next prime is 21015301. The reversal of 21015299 is 99251012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21015299 is a prime.

Together with 21015301, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21015289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10507649 + 10507650.

It is an arithmetic number, because the mean of its divisors is an integer number (10507650).

Almost surely, 2^21015299 is an apocalyptic number.

21015299 is a deficient number, since it is larger than the sum of its proper divisors (1).

21015299 is an equidigital number, since it uses as much as digits as its factorization.

21015299 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 21015299 is about 4584.2446487944. The cubic root of 21015299 is about 275.9593994398.

The spelling of 21015299 in words is "twenty-one million, fifteen thousand, two hundred ninety-nine".