91831087 has 4 divisors (see below), whose sum is σ = 91874376. Its totient is φ = 91787800.

The previous prime is 91831057. The next prime is 91831099. The reversal of 91831087 is 78013819.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78013819 = 13 ⋅6001063.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91831087 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 (91831037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18289 + ... + 22762.

It is an arithmetic number, because the mean of its divisors is an integer number (22968594).

Almost surely, 2^91831087 is an apocalyptic number.

91831087 is a deficient number, since it is larger than the sum of its proper divisors (43289).

91831087 is a wasteful number, since it uses less digits than its factorization.

91831087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43288.

The product of its (nonzero) digits is 12096, while the sum is 37.

The square root of 91831087 is about 9582.8538024954. The cubic root of 91831087 is about 451.1592939795.

The spelling of 91831087 in words is "ninety-one million, eight hundred thirty-one thousand, eighty-seven".