20840439 has 4 divisors (see below), whose sum is σ = 27787256. Its totient is φ = 13893624.

The previous prime is 20840429. The next prime is 20840459. The reversal of 20840439 is 93404802.

It is a happy number.

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

It is not a de Polignac number, because 20840439 - 2⁷ = 20840311 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20840429) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3473404 + ... + 3473409.

It is an arithmetic number, because the mean of its divisors is an integer number (6946814).

Almost surely, 2^20840439 is an apocalyptic number.

20840439 is a deficient number, since it is larger than the sum of its proper divisors (6946817).

20840439 is an equidigital number, since it uses as much as digits as its factorization.

20840439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6946816.

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 20840439 is about 4565.1329663001. The cubic root of 20840439 is about 275.1918837111.

The spelling of 20840439 in words is "twenty million, eight hundred forty thousand, four hundred thirty-nine".