8191531 has 4 divisors (see below), whose sum is σ = 8197272. Its totient is φ = 8185792.

The previous prime is 8191529. The next prime is 8191537. The reversal of 8191531 is 1351918.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1351918 = 2 ⋅675959.

It is a cyclic number.

It is not a de Polignac number, because 8191531 - 2¹ = 8191529 is a prime.

It is a super-2 number, since 2×8191531² = 134202360247922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 8191531.

It is not an unprimeable number, because it can be changed into a prime (8191537) 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, 1116 + ... + 4198.

It is an arithmetic number, because the mean of its divisors is an integer number (2049318).

Almost surely, 2^8191531 is an apocalyptic number.

8191531 is a deficient number, since it is larger than the sum of its proper divisors (5741).

8191531 is a wasteful number, since it uses less digits than its factorization.

8191531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5740.

The product of its digits is 1080, while the sum is 28.

The square root of 8191531 is about 2862.0850790988. The cubic root of 8191531 is about 201.5835208852.

The spelling of 8191531 in words is "eight million, one hundred ninety-one thousand, five hundred thirty-one".