7981991897 has 4 divisors (see below), whose sum is σ = 8707627536. Its totient is φ = 7256356260.

The previous prime is 7981991867. The next prime is 7981991909.

7981991897 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 7981991897 - 2¹⁰ = 7981990873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7981991837) 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, 362817803 + ... + 362817824.

It is an arithmetic number, because the mean of its divisors is an integer number (2176906884).

Almost surely, 2^7981991897 is an apocalyptic number.

It is an amenable number.

7981991897 is a deficient number, since it is larger than the sum of its proper divisors (725635639).

7981991897 is a wasteful number, since it uses less digits than its factorization.

7981991897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 725635638.

The product of its digits is 20575296, while the sum is 68.

The square root of 7981991897 is about 89341.9940285642. The cubic root of 7981991897 is about 1998.4981973266.

The spelling of 7981991897 in words is "seven billion, nine hundred eighty-one million, nine hundred ninety-one thousand, eight hundred ninety-seven".