91351993 has 4 divisors (see below), whose sum is σ = 91751140. Its totient is φ = 90952848.

The previous prime is 91351987. The next prime is 91352017. The reversal of 91351993 is 39915319.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 39915319 = 271 ⋅147289.

It can be written as a sum of positive squares in 2 ways, for example, as 60793209 + 30558784 = 7797^2 + 5528^2 .

It is a cyclic number.

It is not a de Polignac number, because 91351993 - 2⁵ = 91351961 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91351903) 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, 199230 + ... + 199687.

It is an arithmetic number, because the mean of its divisors is an integer number (22937785).

Almost surely, 2^91351993 is an apocalyptic number.

It is an amenable number.

91351993 is a deficient number, since it is larger than the sum of its proper divisors (399147).

91351993 is a wasteful number, since it uses less digits than its factorization.

91351993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399146.

The product of its digits is 32805, while the sum is 40.

The square root of 91351993 is about 9557.8236539497. The cubic root of 91351993 is about 450.3733412017.

The spelling of 91351993 in words is "ninety-one million, three hundred fifty-one thousand, nine hundred ninety-three".