91040040 has 288 divisors, whose sum is σ = 371596680. Its totient is φ = 19160064.

The previous prime is 91040023. The next prime is 91040041. The reversal of 91040040 is 4004019.

It can be written as a sum of positive squares in 4 ways, for example, as 64352484 + 26687556 = 8022^2 + 5166^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 91039995 and 91040022.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91040041) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 229122 + ... + 229518.

Almost surely, 2^91040040 is an apocalyptic number.

91040040 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91040040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (185798340).

91040040 is an abundant number, since it is smaller than the sum of its proper divisors (280556640).

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

91040040 is a wasteful number, since it uses less digits than its factorization.

91040040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441 (or 427 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 91040040 is about 9541.4904496101. The cubic root of 91040040 is about 449.8601046622.

Adding to 91040040 its reverse (4004019), we get a palindrome (95044059).

The spelling of 91040040 in words is "ninety-one million, forty thousand, forty".