20708639 has 8 divisors (see below), whose sum is σ = 24483360. Its totient is φ = 17138016.

The previous prime is 20708599. The next prime is 20708663. The reversal of 20708639 is 93680702.

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

It is not a de Polignac number, because 20708639 - 2²⁰ = 19660063 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20708599 and 20708608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20702639) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50804 + ... + 51209.

It is an arithmetic number, because the mean of its divisors is an integer number (3060420).

Almost surely, 2^20708639 is an apocalyptic number.

20708639 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

20708639 is a deficient number, since it is larger than the sum of its proper divisors (3774721).

20708639 is a wasteful number, since it uses less digits than its factorization.

20708639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102049.

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 20708639 is about 4550.6745653804. The cubic root of 20708639 is about 274.6105296625.

The spelling of 20708639 in words is "twenty million, seven hundred eight thousand, six hundred thirty-nine".