91187993 has 8 divisors (see below), whose sum is σ = 100486848. Its totient is φ = 82215504.

The previous prime is 91187989. The next prime is 91188001. The reversal of 91187993 is 39978119.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91187993 - 2² = 91187989 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (91187923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81005 + ... + 82122.

It is an arithmetic number, because the mean of its divisors is an integer number (12560856).

Almost surely, 2^91187993 is an apocalyptic number.

It is an amenable number.

91187993 is a deficient number, since it is larger than the sum of its proper divisors (9298855).

91187993 is a wasteful number, since it uses less digits than its factorization.

91187993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163183.

The product of its digits is 122472, while the sum is 47.

The square root of 91187993 is about 9549.2404409984. The cubic root of 91187993 is about 450.1036682968.

The spelling of 91187993 in words is "ninety-one million, one hundred eighty-seven thousand, nine hundred ninety-three".