20808139 has 8 divisors (see below), whose sum is σ = 23011632. Its totient is φ = 18656640.

The previous prime is 20808107. The next prime is 20808233. The reversal of 20808139 is 93180802.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20808139 - 2⁵ = 20808107 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20808139.

It is not an unprimeable number, because it can be changed into a prime (20808539) 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 7 ways as a sum of consecutive naturals, for example, 12154 + ... + 13759.

It is an arithmetic number, because the mean of its divisors is an integer number (2876454).

Almost surely, 2^20808139 is an apocalyptic number.

20808139 is a deficient number, since it is larger than the sum of its proper divisors (2203493).

20808139 is a wasteful number, since it uses less digits than its factorization.

20808139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25997.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 20808139 is about 4561.5939100275. The cubic root of 20808139 is about 275.0496395240.

The spelling of 20808139 in words is "twenty million, eight hundred eight thousand, one hundred thirty-nine".