2191728 has 80 divisors (see below), whose sum is σ = 7070976. Its totient is φ = 568320.

The previous prime is 2191727. The next prime is 2191799. The reversal of 2191728 is 8271912.

It is a junction number, because it is equal to n+sod(n) for n = 2191695 and 2191704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2191723) 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, 3400 + ... + 3992.

2^2191728 is an apocalyptic number.

2191728 is a gapful number since it is divisible by the number (28) 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 2191728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3535488).

2191728 is an abundant number, since it is smaller than the sum of its proper divisors (4879248).

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

2191728 is a wasteful number, since it uses less digits than its factorization.

2191728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 622 (or 616 counting only the distinct ones).

The product of its digits is 2016, while the sum is 30.

The square root of 2191728 is about 1480.4485806674. The cubic root of 2191728 is about 129.8959324933.

It can be divided in two parts, 21917 and 28, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 2191728 in words is "two million, one hundred ninety-one thousand, seven hundred twenty-eight".