91323540 has 216 divisors, whose sum is σ = 348566400. Its totient is φ = 18944640.

The previous prime is 91323539. The next prime is 91323553. The reversal of 91323540 is 4532319.

91323540 is a `hidden beast` number, since 91 + 32 + 3 + 540 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 152161 + ... + 152759.

Almost surely, 2^91323540 is an apocalyptic number.

91323540 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91323540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (174283200).

91323540 is an abundant number, since it is smaller than the sum of its proper divisors (257242860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91323540 is a wasteful number, since it uses less digits than its factorization.

91323540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643 (or 627 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

The square root of 91323540 is about 9556.3350715638. The cubic root of 91323540 is about 450.3265777508.

Adding to 91323540 its reverse (4532319), we get a palindrome (95855859).

The spelling of 91323540 in words is "ninety-one million, three hundred twenty-three thousand, five hundred forty".