1666181 has 4 divisors (see below), whose sum is σ = 1817664. Its totient is φ = 1514700.

The previous prime is 1666177. The next prime is 1666201. The reversal of 1666181 is 1816661.

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 not a de Polignac number, because 1666181 - 2² = 1666177 is a prime.

It is a super-2 number, since 2×1666181² = 5552318249522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75725 + ... + 75746.

It is an arithmetic number, because the mean of its divisors is an integer number (454416).

2^1666181 is an apocalyptic number.

1666181 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1666181 is a deficient number, since it is larger than the sum of its proper divisors (151483).

1666181 is a wasteful number, since it uses less digits than its factorization.

1666181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151482.

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

The square root of 1666181 is about 1290.8063371397. The cubic root of 1666181 is about 118.5515926008.

The spelling of 1666181 in words is "one million, six hundred sixty-six thousand, one hundred eighty-one".