91491840 has 360 divisors, whose sum is σ = 364818168. Its totient is φ = 21012480.

The previous prime is 91491817. The next prime is 91491863. The reversal of 91491840 is 4819419.

91491840 is a `hidden beast` number, since 91 + 491 + 84 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (91491817) and next prime (91491863).

It is a tau number, because it is divible by the number of its divisors (360).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 91491795 and 91491804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4815351 + ... + 4815369.

Almost surely, 2^91491840 is an apocalyptic number.

91491840 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 91491840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (182409084).

91491840 is an abundant number, since it is smaller than the sum of its proper divisors (273326328).

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

91491840 is a wasteful number, since it uses less digits than its factorization.

91491840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78 (or 40 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 91491840 is about 9565.1366953118. The cubic root of 91491840 is about 450.6030433547.

The spelling of 91491840 in words is "ninety-one million, four hundred ninety-one thousand, eight hundred forty".