91321840 has 20 divisors (see below), whose sum is σ = 212323464. Its totient is φ = 36528704.

The previous prime is 91321837. The next prime is 91321843. The reversal of 91321840 is 4812319.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (91321837) and next prime (91321843).

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 91321799 and 91321808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91321843) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 570682 + ... + 570841.

Almost surely, 2^91321840 is an apocalyptic number.

It is an amenable number.

91321840 is an abundant number, since it is smaller than the sum of its proper divisors (121001624).

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

91321840 is a wasteful number, since it uses less digits than its factorization.

91321840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1141536 (or 1141530 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 91321840 is about 9556.2461249175. The cubic root of 91321840 is about 450.3237834368.

The spelling of 91321840 in words is "ninety-one million, three hundred twenty-one thousand, eight hundred forty".