1661328 has 60 divisors (see below), whose sum is σ = 4739280. Its totient is φ = 543168.

The previous prime is 1661327. The next prime is 1661333. The reversal of 1661328 is 8231661.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (1661327) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11883 + ... + 12021.

It is an arithmetic number, because the mean of its divisors is an integer number (78988).

2^1661328 is an apocalyptic number.

1661328 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 1661328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2369640).

1661328 is an abundant number, since it is smaller than the sum of its proper divisors (3077952).

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

1661328 is a wasteful number, since it uses less digits than its factorization.

1661328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236 (or 227 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 1661328 is about 1288.9251335900. The cubic root of 1661328 is about 118.4363809554.

Adding to 1661328 its reverse (8231661), we get a palindrome (9892989).

It can be divided in two parts, 16613 and 28, that added together give a square (16641 = 129²).

The spelling of 1661328 in words is "one million, six hundred sixty-one thousand, three hundred twenty-eight".