331666 has 4 divisors (see below), whose sum is σ = 497502. Its totient is φ = 165832.

The previous prime is 331663. The next prime is 331691. The reversal of 331666 is 666133.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 666133 = 13 ⋅51241.

It can be written as a sum of positive squares in only one way, i.e., 326041 + 5625 = 571^2 + 75^2 .

It is a super-2 number, since 2×331666² = 220004671112, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 331666.

It is not an unprimeable number, because it can be changed into a prime (331663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82915 + ... + 82918.

2³³¹⁶⁶⁶ is an apocalyptic number.

331666 is a deficient number, since it is larger than the sum of its proper divisors (165836).

331666 is a wasteful number, since it uses less digits than its factorization.

331666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165835.

The product of its digits is 1944, while the sum is 25.

The square root of 331666 is about 575.9045059730. The cubic root of 331666 is about 69.2203277067.

Adding to 331666 its reverse (666133), we get a palindrome (997799).

The spelling of 331666 in words is "three hundred thirty-one thousand, six hundred sixty-six".