21331339 has 2 divisors, whose sum is σ = 21331340. Its totient is φ = 21331338.

The previous prime is 21331333. The next prime is 21331361. The reversal of 21331339 is 93313312.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21331339 is a prime.

It is not a weakly prime, because it can be changed into another prime (21331333) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10665669 + 10665670.

It is an arithmetic number, because the mean of its divisors is an integer number (10665670).

Almost surely, 2^21331339 is an apocalyptic number.

21331339 is a deficient number, since it is larger than the sum of its proper divisors (1).

21331339 is an equidigital number, since it uses as much as digits as its factorization.

21331339 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1458, while the sum is 25.

The square root of 21331339 is about 4618.5862555548. The cubic root of 21331339 is about 277.3358670115.

The spelling of 21331339 in words is "twenty-one million, three hundred thirty-one thousand, three hundred thirty-nine".