91057557 has 24 divisors (see below), whose sum is σ = 129808224. Its totient is φ = 56761056.

The previous prime is 91057553. The next prime is 91057601. The reversal of 91057557 is 75575019.

It is not a de Polignac number, because 91057557 - 2² = 91057553 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91057553) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 89383 + ... + 90395.

It is an arithmetic number, because the mean of its divisors is an integer number (5408676).

Almost surely, 2^91057557 is an apocalyptic number.

It is an amenable number.

91057557 is a deficient number, since it is larger than the sum of its proper divisors (38750667).

91057557 is a wasteful number, since it uses less digits than its factorization.

91057557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1137 (or 1118 counting only the distinct ones).

The product of its (nonzero) digits is 55125, while the sum is 39.

The square root of 91057557 is about 9542.4083438092. The cubic root of 91057557 is about 449.8889553163. Note that the first 3 decimals are identical.

The spelling of 91057557 in words is "ninety-one million, fifty-seven thousand, five hundred fifty-seven".