91240640 has 56 divisors (see below), whose sum is σ = 218358720. Its totient is φ = 36313088.

The previous prime is 91240637. The next prime is 91240651. The reversal of 91240640 is 4604219.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75884 + ... + 77076.

Almost surely, 2^91240640 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 91240640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109179360).

91240640 is an abundant number, since it is smaller than the sum of its proper divisors (127118080).

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

91240640 is a wasteful number, since it uses less digits than its factorization.

91240640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1449 (or 1439 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 91240640 is about 9551.9966499157. The cubic root of 91240640 is about 450.1902734448.

Adding to 91240640 its reverse (4604219), we get a palindrome (95844859).

The spelling of 91240640 in words is "ninety-one million, two hundred forty thousand, six hundred forty".