20511409839 has 4 divisors (see below), whose sum is σ = 27348546456. Its totient is φ = 13674273224.

The previous prime is 20511409819. The next prime is 20511409843. The reversal of 20511409839 is 93890411502.

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

It is a cyclic number.

It is not a de Polignac number, because 20511409839 - 2²⁴ = 20494632623 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20511409839.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20511409819) 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, 3418568304 + ... + 3418568309.

It is an arithmetic number, because the mean of its divisors is an integer number (6837136614).

Almost surely, 2^20511409839 is an apocalyptic number.

20511409839 is a deficient number, since it is larger than the sum of its proper divisors (6837136617).

20511409839 is an equidigital number, since it uses as much as digits as its factorization.

20511409839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6837136616.

The product of its (nonzero) digits is 77760, while the sum is 42.

The spelling of 20511409839 in words is "twenty billion, five hundred eleven million, four hundred nine thousand, eight hundred thirty-nine".