1991088 has 80 divisors (see below), whose sum is σ = 6249600. Its totient is φ = 601920.

The previous prime is 1991071. The next prime is 1991089. The reversal of 1991088 is 8801991.

1991088 = 42³ + 43³ + ... + 57³.

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

It is not an unprimeable number, because it can be changed into a prime (1991089) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4543 + ... + 4961.

It is an arithmetic number, because the mean of its divisors is an integer number (78120).

2^1991088 is an apocalyptic number.

1991088 is a gapful number since it is divisible by the number (18) 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 1991088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3124800).

1991088 is an abundant number, since it is smaller than the sum of its proper divisors (4258512).

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

1991088 is a wasteful number, since it uses less digits than its factorization.

1991088 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 447 (or 435 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 36.

The square root of 1991088 is about 1411.0591766471. The cubic root of 1991088 is about 125.8046860604.

The spelling of 1991088 in words is "one million, nine hundred ninety-one thousand, eighty-eight".