7978517689128 has 128 divisors (see below), whose sum is σ = 23042218003200. Its totient is φ = 2254999025664.

The previous prime is 7978517689049. The next prime is 7978517689147. The reversal of 7978517689128 is 8219867158797.

It is a Cunningham number, because it is equal to 2824627²-1.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10945426 + ... + 11651582.

It is an arithmetic number, because the mean of its divisors is an integer number (180017328150).

Almost surely, 2^{7978517689128} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7978517689128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11521109001600).

7978517689128 is an abundant number, since it is smaller than the sum of its proper divisors (15063700314072).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

7978517689128 is a wasteful number, since it uses less digits than its factorization.

7978517689128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 706899 (or 706895 counting only the distinct ones).

The product of its digits is 853493760, while the sum is 78.

The spelling of 7978517689128 in words is "seven trillion, nine hundred seventy-eight billion, five hundred seventeen million, six hundred eighty-nine thousand, one hundred twenty-eight".