1665280 has 36 divisors (see below), whose sum is σ = 3991932. Its totient is φ = 665600.

The previous prime is 1665277. The next prime is 1665311. The reversal of 1665280 is 825661.

It can be written as a sum of positive squares in 2 ways, for example, as 186624 + 1478656 = 432^2 + 1216^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 630 + ... + 1930.

It is an arithmetic number, because the mean of its divisors is an integer number (110887).

2^1665280 is an apocalyptic number.

1665280 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 1665280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1995966).

1665280 is an abundant number, since it is smaller than the sum of its proper divisors (2326652).

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

1665280 is an equidigital number, since it uses as much as digits as its factorization.

1665280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1322 (or 1308 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 1665280 is about 1290.4572832915. The cubic root of 1665280 is about 118.5302195238.

It can be divided in two parts, 1 and 665280, that added together give a triangular number (665281 = T₁₁₅₃).

The spelling of 1665280 in words is "one million, six hundred sixty-five thousand, two hundred eighty".