7991397881 has 8 divisors (see below), whose sum is σ = 8003803200. Its totient is φ = 7979005008.

The previous prime is 7991397857. The next prime is 7991397901. The reversal of 7991397881 is 1887931997.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7991397881 is a prime.

It is a super-2 number, since 2×7991397881² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7991394881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2766620 + ... + 2769506.

It is an arithmetic number, because the mean of its divisors is an integer number (1000475400).

Almost surely, 2^7991397881 is an apocalyptic number.

It is an amenable number.

7991397881 is a deficient number, since it is larger than the sum of its proper divisors (12405319).

7991397881 is a wasteful number, since it uses less digits than its factorization.

7991397881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6223.

The product of its digits is 6858432, while the sum is 62.

The square root of 7991397881 is about 89394.6188593027. The cubic root of 7991397881 is about 1999.2828996643.

The spelling of 7991397881 in words is "seven billion, nine hundred ninety-one million, three hundred ninety-seven thousand, eight hundred eighty-one".