91531840 has 56 divisors (see below), whose sum is σ = 225015552. Its totient is φ = 35427840.

The previous prime is 91531837. The next prime is 91531879. The reversal of 91531840 is 4813519.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5307 + ... + 14533.

Almost surely, 2^91531840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91531840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112507776).

91531840 is an abundant number, since it is smaller than the sum of its proper divisors (133483712).

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

91531840 is a wasteful number, since it uses less digits than its factorization.

91531840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9275 (or 9265 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 91531840 is about 9567.2273935556. The cubic root of 91531840 is about 450.6687012890.

The spelling of 91531840 in words is "ninety-one million, five hundred thirty-one thousand, eight hundred forty".