1811666 has 4 divisors (see below), whose sum is σ = 2717502. Its totient is φ = 905832.

The previous prime is 1811657. The next prime is 1811681. The reversal of 1811666 is 6661181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6661181 = 463 ⋅14387.

It can be written as a sum of positive squares in only one way, i.e., 1256641 + 555025 = 1121^2 + 745^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 452915 + ... + 452918.

2^1811666 is an apocalyptic number.

1811666 is a deficient number, since it is larger than the sum of its proper divisors (905836).

1811666 is an equidigital number, since it uses as much as digits as its factorization.

1811666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 905835.

The product of its digits is 1728, while the sum is 29.

The square root of 1811666 is about 1345.9814263206. The cubic root of 1811666 is about 121.9062703894.

The spelling of 1811666 in words is "one million, eight hundred eleven thousand, six hundred sixty-six".