91040640 has 64 divisors (see below), whose sum is σ = 290198160. Its totient is φ = 24276992.

The previous prime is 91040617. The next prime is 91040641. The reversal of 91040640 is 4604019.

It is a tau number, because it is divible by the number of its divisors (64).

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 91040640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91040641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21789 + ... + 25628.

Almost surely, 2^91040640 is an apocalyptic number.

It is an amenable number.

91040640 is an abundant number, since it is smaller than the sum of its proper divisors (199157520).

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

91040640 is a wasteful number, since it uses less digits than its factorization.

91040640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47439 (or 47427 counting only the distinct ones).

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

The square root of 91040640 is about 9541.5218911870. The cubic root of 91040640 is about 449.8610929287.

Adding to 91040640 its reverse (4604019), we get a palindrome (95644659).

The spelling of 91040640 in words is "ninety-one million, forty thousand, six hundred forty".