91188057 has 4 divisors (see below), whose sum is σ = 121584080. Its totient is φ = 60792036.

The previous prime is 91188047. The next prime is 91188067. The reversal of 91188057 is 75088119.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75088119 = 3 ⋅25029373.

It is an interprime number because it is at equal distance from previous prime (91188047) and next prime (91188067).

It is not a de Polignac number, because 91188057 - 2¹⁴ = 91171673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91188007) 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, 15198007 + ... + 15198012.

It is an arithmetic number, because the mean of its divisors is an integer number (30396020).

Almost surely, 2^91188057 is an apocalyptic number.

It is an amenable number.

91188057 is a deficient number, since it is larger than the sum of its proper divisors (30396023).

91188057 is a wasteful number, since it uses less digits than its factorization.

91188057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30396022.

The product of its (nonzero) digits is 20160, while the sum is 39.

The square root of 91188057 is about 9549.2437920497. The cubic root of 91188057 is about 450.1037735980.

The spelling of 91188057 in words is "ninety-one million, one hundred eighty-eight thousand, fifty-seven".