91231187 has 4 divisors (see below), whose sum is σ = 94377120. Its totient is φ = 88085256.

The previous prime is 91231181. The next prime is 91231211. The reversal of 91231187 is 78113219.

Added to its reverse (78113219) it gives a triangular number (169344406 = T₁₈₄₀₃).

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78113219 = 313 ⋅249563.

It is a cyclic number.

It is not a de Polignac number, because 91231187 - 2⁶ = 91231123 is a prime.

It is a Duffinian number.

It is a plaindrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (91231181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1572923 + ... + 1572980.

It is an arithmetic number, because the mean of its divisors is an integer number (23594280).

Almost surely, 2^91231187 is an apocalyptic number.

91231187 is a deficient number, since it is larger than the sum of its proper divisors (3145933).

91231187 is a wasteful number, since it uses less digits than its factorization.

91231187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3145932.

The product of its digits is 3024, while the sum is 32.

The square root of 91231187 is about 9551.5018190858. The cubic root of 91231187 is about 450.1747255646.

Adding to 91231187 its reverse (78113219), we get a triangular number (169344406 = T₁₈₄₀₃).

The spelling of 91231187 in words is "ninety-one million, two hundred thirty-one thousand, one hundred eighty-seven".