91604040 has 128 divisors (see below), whose sum is σ = 310262400. Its totient is φ = 21432320.

The previous prime is 91604021. The next prime is 91604047. The reversal of 91604040 is 4040619.

It is a Cunningham number, because it is equal to 9571²-1.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 91604040.

It is not an unprimeable number, because it can be changed into a prime (91604047) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 37084 + ... + 39476.

It is an arithmetic number, because the mean of its divisors is an integer number (2423925).

Almost surely, 2^91604040 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 91604040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (155131200).

91604040 is an abundant number, since it is smaller than the sum of its proper divisors (218658360).

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

91604040 is a wasteful number, since it uses less digits than its factorization.

91604040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2447 (or 2443 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 91604040 is about 9570.9999477589. Note that the first 4 decimals coincide. The cubic root of 91604040 is about 450.7871654527.

Adding to 91604040 its reverse (4040619), we get a palindrome (95644659).

The spelling of 91604040 in words is "ninety-one million, six hundred four thousand, forty".