91640640 has 224 divisors, whose sum is σ = 358444800. Its totient is φ = 19316736.

The previous prime is 91640603. The next prime is 91640663. The reversal of 91640640 is 4604619.

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 91640598 and 91640607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 86836 + ... + 87884.

It is an arithmetic number, because the mean of its divisors is an integer number (1600200).

Almost surely, 2^91640640 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 91640640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (179222400).

91640640 is an abundant number, since it is smaller than the sum of its proper divisors (266804160).

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

91640640 is a wasteful number, since it uses less digits than its factorization.

91640640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1089 (or 1079 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 91640640 is about 9572.9117827336. The cubic root of 91640640 is about 450.8471941494.

The spelling of 91640640 in words is "ninety-one million, six hundred forty thousand, six hundred forty".