7861991688 has 96 divisors (see below), whose sum is σ = 21816194400. Its totient is φ = 2556417024.

The previous prime is 7861991671. The next prime is 7861991689. The reversal of 7861991688 is 8861991687.

7861991688 is a `hidden beast` number, since 7 + 8 + 619 + 9 + 1 + 6 + 8 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (7861991689) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3896856 + ... + 3898872.

It is an arithmetic number, because the mean of its divisors is an integer number (227252025).

Almost surely, 2^7861991688 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 7861991688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10908097200).

7861991688 is an abundant number, since it is smaller than the sum of its proper divisors (13954202712).

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

7861991688 is a wasteful number, since it uses less digits than its factorization.

7861991688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3331 (or 3324 counting only the distinct ones).

The product of its digits is 10450944, while the sum is 63.

The square root of 7861991688 is about 88667.8729191132. The cubic root of 7861991688 is about 1988.4325331722.

Subtracting 7861991688 from its reverse (8861991687), we obtain a palindrome (999999999).

The spelling of 7861991688 in words is "seven billion, eight hundred sixty-one million, nine hundred ninety-one thousand, six hundred eighty-eight".