20439823 has 4 divisors (see below), whose sum is σ = 20450800. Its totient is φ = 20428848.

The previous prime is 20439803. The next prime is 20439841. The reversal of 20439823 is 32893402.

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 a de Polignac number, because none of the positive numbers 2^k-20439823 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 (20439803) 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, 1923 + ... + 6676.

It is an arithmetic number, because the mean of its divisors is an integer number (5112700).

Almost surely, 2^20439823 is an apocalyptic number.

20439823 is a deficient number, since it is larger than the sum of its proper divisors (10977).

20439823 is an equidigital number, since it uses as much as digits as its factorization.

20439823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10976.

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 20439823 is about 4521.0422470930. The cubic root of 20439823 is about 273.4171236604.

The spelling of 20439823 in words is "twenty million, four hundred thirty-nine thousand, eight hundred twenty-three".