1666191 has 8 divisors (see below), whose sum is σ = 2229040. Its totient is φ = 1107072.

The previous prime is 1666177. The next prime is 1666201. The reversal of 1666191 is 1916661.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1666191 - 2⁶ = 1666127 is a prime.

It is a Duffinian number.

1666191 is a lucky 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 7 ways as a sum of consecutive naturals, for example, 375 + ... + 1863.

It is an arithmetic number, because the mean of its divisors is an integer number (278630).

2^1666191 is an apocalyptic number.

1666191 is a deficient number, since it is larger than the sum of its proper divisors (562849).

1666191 is a wasteful number, since it uses less digits than its factorization.

1666191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1865.

The product of its digits is 1944, while the sum is 30.

The square root of 1666191 is about 1290.8102106816. The cubic root of 1666191 is about 118.5518297726.

It can be divided in two parts, 16661 and 91, that multiplied together give a palindrome (1516151).

The spelling of 1666191 in words is "one million, six hundred sixty-six thousand, one hundred ninety-one".