7871991787 has 4 divisors (see below), whose sum is σ = 8587627416. Its totient is φ = 7156356160.

The previous prime is 7871991781. The next prime is 7871991793.

7871991787 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (7871991781) and next prime (7871991793).

It is a cyclic number.

It is not a de Polignac number, because 7871991787 - 2¹¹ = 7871989739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7871991781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 357817798 + ... + 357817819.

It is an arithmetic number, because the mean of its divisors is an integer number (2146906854).

Almost surely, 2^7871991787 is an apocalyptic number.

7871991787 is a deficient number, since it is larger than the sum of its proper divisors (715635629).

7871991787 is a wasteful number, since it uses less digits than its factorization.

7871991787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 715635628.

The product of its digits is 12446784, while the sum is 64.

The square root of 7871991787 is about 88724.2457674338. The cubic root of 7871991787 is about 1989.2752414913.

The spelling of 7871991787 in words is "seven billion, eight hundred seventy-one million, nine hundred ninety-one thousand, seven hundred eighty-seven".