21347239 has 2 divisors, whose sum is σ = 21347240. Its totient is φ = 21347238.

The previous prime is 21347233. The next prime is 21347267. The reversal of 21347239 is 93274312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21347239 - 2⁷ = 21347111 is a prime.

It is a super-2 number, since 2×21347239² = 911409225846242, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21347239.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21347233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10673619 + 10673620.

It is an arithmetic number, because the mean of its divisors is an integer number (10673620).

Almost surely, 2^21347239 is an apocalyptic number.

21347239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21347239 is an equidigital number, since it uses as much as digits as its factorization.

21347239 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 31.

The square root of 21347239 is about 4620.3072408661. The cubic root of 21347239 is about 277.4047569691.

The spelling of 21347239 in words is "twenty-one million, three hundred forty-seven thousand, two hundred thirty-nine".