1661105 has 4 divisors (see below), whose sum is σ = 1993332. Its totient is φ = 1328880.

The previous prime is 1661069. The next prime is 1661111. The reversal of 1661105 is 5011661.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1032256 + 628849 = 1016^2 + 793^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1661105 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166106 + ... + 166115.

It is an arithmetic number, because the mean of its divisors is an integer number (498333).

2^1661105 is an apocalyptic number.

It is an amenable number.

1661105 is a deficient number, since it is larger than the sum of its proper divisors (332227).

1661105 is an equidigital number, since it uses as much as digits as its factorization.

1661105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332226.

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 1661105 is about 1288.8386244988. The cubic root of 1661105 is about 118.4310814812.

Adding to 1661105 its reverse (5011661), we get a palindrome (6672766).

The spelling of 1661105 in words is "one million, six hundred sixty-one thousand, one hundred five".