7899991000 has 128 divisors (see below), whose sum is σ = 21228480000. Its totient is φ = 2721456000.

The previous prime is 7899990997. The next prime is 7899991031. The reversal of 7899991000 is 1999987.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 190101 + ... + 227899.

It is an arithmetic number, because the mean of its divisors is an integer number (165847500).

Almost surely, 2^7899991000 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 7899991000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10614240000).

7899991000 is an abundant number, since it is smaller than the sum of its proper divisors (13328489000).

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

7899991000 is a wasteful number, since it uses less digits than its factorization.

7899991000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37850 (or 37836 counting only the distinct ones).

The product of its (nonzero) digits is 367416, while the sum is 52.

The square root of 7899991000 is about 88881.8935441859. The cubic root of 7899991000 is about 1991.6309449738.

It can be divided in two parts, 7899 and 991000, that added together give a palindrome (998899).

The spelling of 7899991000 in words is "seven billion, eight hundred ninety-nine million, nine hundred ninety-one thousand".