21113399 has 2 divisors, whose sum is σ = 21113400. Its totient is φ = 21113398.

The previous prime is 21113357. The next prime is 21113423. The reversal of 21113399 is 99331112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21113399 - 2²⁰ = 20064823 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21113329) 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, 10556699 + 10556700.

It is an arithmetic number, because the mean of its divisors is an integer number (10556700).

Almost surely, 2^21113399 is an apocalyptic number.

21113399 is a deficient number, since it is larger than the sum of its proper divisors (1).

21113399 is an equidigital number, since it uses as much as digits as its factorization.

21113399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1458, while the sum is 29.

The square root of 21113399 is about 4594.9318819761. The cubic root of 21113399 is about 276.3881284069.

It can be divided in two parts, 21113 and 399, that added together give a palindrome (21512).

The spelling of 21113399 in words is "twenty-one million, one hundred thirteen thousand, three hundred ninety-nine".