21791339 has 4 divisors (see below), whose sum is σ = 21801360. Its totient is φ = 21781320.

The previous prime is 21791333. The next prime is 21791353. The reversal of 21791339 is 93319712.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21791339 - 2²⁰ = 20742763 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21791299 and 21791308.

It is not an unprimeable number, because it can be changed into a prime (21791333) 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 in 3 ways as a sum of consecutive naturals, for example, 224 + ... + 6605.

It is an arithmetic number, because the mean of its divisors is an integer number (5450340).

Almost surely, 2^21791339 is an apocalyptic number.

21791339 is a deficient number, since it is larger than the sum of its proper divisors (10021).

21791339 is an equidigital number, since it uses as much as digits as its factorization.

21791339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10020.

The product of its digits is 10206, while the sum is 35.

The square root of 21791339 is about 4668.1194286350. The cubic root of 21791339 is about 279.3152442735.

The spelling of 21791339 in words is "twenty-one million, seven hundred ninety-one thousand, three hundred thirty-nine".