20817051839 has 4 divisors (see below), whose sum is σ = 21209826456. Its totient is φ = 20424277224.

The previous prime is 20817051781. The next prime is 20817051847. The reversal of 20817051839 is 93815071802.

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 20817051839 - 2²⁴ = 20800274623 is a prime.

It is a super-2 number, since 2×20817051839² (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 20817051839.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20817651839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 196387229 + ... + 196387334.

It is an arithmetic number, because the mean of its divisors is an integer number (5302456614).

Almost surely, 2^20817051839 is an apocalyptic number.

20817051839 is a deficient number, since it is larger than the sum of its proper divisors (392774617).

20817051839 is an equidigital number, since it uses as much as digits as its factorization.

20817051839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392774616.

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

The spelling of 20817051839 in words is "twenty billion, eight hundred seventeen million, fifty-one thousand, eight hundred thirty-nine".