20508817139 has 4 divisors (see below), whose sum is σ = 21216017760. Its totient is φ = 19801616520.

The previous prime is 20508817111. The next prime is 20508817163. The reversal of 20508817139 is 93171880502.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20508817139 is a prime.

It is a super-2 number, since 2×20508817139² (a number of 21 digits) contains 22 as substring.

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 20508817139.

It is not an unprimeable number, because it can be changed into a prime (20508817339) 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, 353600267 + ... + 353600324.

It is an arithmetic number, because the mean of its divisors is an integer number (5304004440).

Almost surely, 2^20508817139 is an apocalyptic number.

20508817139 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

20508817139 is a deficient number, since it is larger than the sum of its proper divisors (707200621).

20508817139 is an equidigital number, since it uses as much as digits as its factorization.

20508817139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 707200620.

The product of its (nonzero) digits is 120960, while the sum is 44.

The spelling of 20508817139 in words is "twenty billion, five hundred eight million, eight hundred seventeen thousand, one hundred thirty-nine".