16978139838965 has 4 divisors (see below), whose sum is σ = 20373767806764. Its totient is φ = 13582511871168.

The previous prime is 16978139838929. The next prime is 16978139838973. The reversal of 16978139838965 is 56983893187961.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7624567832644 + 9353572006321 = 2761262^2 + 3058361^2 .

It is a cyclic number.

It is not a de Polignac number, because 16978139838965 - 2¹² = 16978139834869 is a prime.

It is a super-2 number, since 2×16978139838965² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1697813983892 + ... + 1697813983901.

It is an arithmetic number, because the mean of its divisors is an integer number (5093441951691).

Almost surely, 2^{16978139838965} is an apocalyptic number.

It is an amenable number.

16978139838965 is a deficient number, since it is larger than the sum of its proper divisors (3395627967799).

16978139838965 is an equidigital number, since it uses as much as digits as its factorization.

16978139838965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3395627967798.

The product of its digits is 4232632320, while the sum is 83.

The spelling of 16978139838965 in words is "sixteen trillion, nine hundred seventy-eight billion, one hundred thirty-nine million, eight hundred thirty-eight thousand, nine hundred sixty-five".