1665181 has 4 divisors (see below), whose sum is σ = 1903072. Its totient is φ = 1427292.

The previous prime is 1665173. The next prime is 1665197. The reversal of 1665181 is 1815661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1665181 - 2³ = 1665173 is a prime.

It is a super-2 number, since 2×1665181² = 5545655525522, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665121) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 118935 + ... + 118948.

It is an arithmetic number, because the mean of its divisors is an integer number (475768).

2^1665181 is an apocalyptic number.

It is an amenable number.

1665181 is a deficient number, since it is larger than the sum of its proper divisors (237891).

1665181 is an equidigital number, since it uses as much as digits as its factorization.

1665181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237890.

The product of its digits is 1440, while the sum is 28.

The square root of 1665181 is about 1290.4189242258. The cubic root of 1665181 is about 118.5278706246.

The spelling of 1665181 in words is "one million, six hundred sixty-five thousand, one hundred eighty-one".