21290339 has 4 divisors (see below), whose sum is σ = 24331824. Its totient is φ = 18248856.

The previous prime is 21290323. The next prime is 21290351. The reversal of 21290339 is 93309212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21290339 - 2⁴ = 21290323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21290039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1520732 + ... + 1520745.

It is an arithmetic number, because the mean of its divisors is an integer number (6082956).

Almost surely, 2^21290339 is an apocalyptic number.

21290339 is a deficient number, since it is larger than the sum of its proper divisors (3041485).

21290339 is an equidigital number, since it uses as much as digits as its factorization.

21290339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3041484.

The product of its (nonzero) digits is 2916, while the sum is 29.

The square root of 21290339 is about 4614.1455330321. The cubic root of 21290339 is about 277.1580681492.

The spelling of 21290339 in words is "twenty-one million, two hundred ninety thousand, three hundred thirty-nine".