1091820 has 48 divisors (see below), whose sum is σ = 3161088. Its totient is φ = 281280.

The previous prime is 1091809. The next prime is 1091837. The reversal of 1091820 is 281901.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1567 + ... + 2153.

It is an arithmetic number, because the mean of its divisors is an integer number (65856).

2^1091820 is an apocalyptic number.

1091820 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 1091820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1580544).

1091820 is an abundant number, since it is smaller than the sum of its proper divisors (2069268).

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

1091820 is a wasteful number, since it uses less digits than its factorization.

1091820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 630 (or 628 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 1091820 is about 1044.9019092719. The cubic root of 1091820 is about 102.9714942953.

The spelling of 1091820 in words is "one million, ninety-one thousand, eight hundred twenty".