8187991373 has 4 divisors (see below), whose sum is σ = 8188234620. Its totient is φ = 8187748128.

The previous prime is 8187991351. The next prime is 8187991391. The reversal of 8187991373 is 3731997818.

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

It can be written as a sum of positive squares in 2 ways, for example, as 70341769 + 8117649604 = 8387^2 + 90098^2 .

It is a cyclic number.

It is not a de Polignac number, because 8187991373 - 2¹⁸ = 8187729229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8187991303) 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, 61088 + ... + 141801.

It is an arithmetic number, because the mean of its divisors is an integer number (2047058655).

Almost surely, 2^8187991373 is an apocalyptic number.

It is an amenable number.

8187991373 is a deficient number, since it is larger than the sum of its proper divisors (243247).

8187991373 is a wasteful number, since it uses less digits than its factorization.

8187991373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243246.

The product of its digits is 2286144, while the sum is 56.

The square root of 8187991373 is about 90487.5205373647. The cubic root of 8187991373 is about 2015.5448141049.

The spelling of 8187991373 in words is "eight billion, one hundred eighty-seven million, nine hundred ninety-one thousand, three hundred seventy-three".