21331899 has 12 divisors (see below), whose sum is σ = 30857112. Its totient is φ = 14200800.

The previous prime is 21331897. The next prime is 21331901. The reversal of 21331899 is 99813312.

It is an interprime number because it is at equal distance from previous prime (21331897) and next prime (21331901).

It is not a de Polignac number, because 21331899 - 2¹ = 21331897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21331897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7519 + ... + 9959.

It is an arithmetic number, because the mean of its divisors is an integer number (2571426).

Almost surely, 2^21331899 is an apocalyptic number.

21331899 is a deficient number, since it is larger than the sum of its proper divisors (9525213).

21331899 is a wasteful number, since it uses less digits than its factorization.

21331899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3418 (or 3415 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 21331899 is about 4618.6468797690. The cubic root of 21331899 is about 277.3382939060.

The spelling of 21331899 in words is "twenty-one million, three hundred thirty-one thousand, eight hundred ninety-nine".