7899779988 has 60 divisors (see below), whose sum is σ = 20959875552. Its totient is φ = 2593950480.

The previous prime is 7899779969. The next prime is 7899780019. The reversal of 7899779988 is 8899779987.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 160248 + ... + 203663.

Almost surely, 2^7899779988 is an apocalyptic number.

It is an amenable number.

7899779988 is an abundant number, since it is smaller than the sum of its proper divisors (13060095564).

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

7899779988 is a wasteful number, since it uses less digits than its factorization.

7899779988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363994 (or 363983 counting only the distinct ones).

The product of its digits is 1152216576, while the sum is 81.

The square root of 7899779988 is about 88880.7065003424. The cubic root of 7899779988 is about 1991.6132123894.

Subtracting 7899779988 from its reverse (8899779987), we obtain a palindrome (999999999).

The spelling of 7899779988 in words is "seven billion, eight hundred ninety-nine million, seven hundred seventy-nine thousand, nine hundred eighty-eight".