1991082240 has 216 divisors, whose sum is σ = 7873389888. Its totient is φ = 455086080.

The previous prime is 1991082179. The next prime is 1991082241. The reversal of 1991082240 is 422801991.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1991082195 and 1991082204.

It is not an unprimeable number, because it can be changed into a prime (1991082241) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 68295 + ... + 92985.

Almost surely, 2^1991082240 is an apocalyptic number.

1991082240 is a gapful number since it is divisible by the number (10) 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 1991082240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3936694944).

1991082240 is an abundant number, since it is smaller than the sum of its proper divisors (5882307648).

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

1991082240 is a wasteful number, since it uses less digits than its factorization.

1991082240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24725 (or 24708 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 1991082240 is about 44621.5445721010. The cubic root of 1991082240 is about 1258.0456474717.

The spelling of 1991082240 in words is "one billion, nine hundred ninety-one million, eighty-two thousand, two hundred forty".