1660221 has 12 divisors (see below), whose sum is σ = 2481180. Its totient is φ = 1068480.

The previous prime is 1660207. The next prime is 1660229. The reversal of 1660221 is 1220661.

It is a happy number.

1660221 is a `hidden beast` number, since 1 + 660 + 2 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 632025 + 1028196 = 795^2 + 1014^2 .

It is not a de Polignac number, because 1660221 - 2⁵ = 1660189 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1660194 and 1660203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1660229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2920 + ... + 3441.

It is an arithmetic number, because the mean of its divisors is an integer number (206765).

2^1660221 is an apocalyptic number.

It is an amenable number.

1660221 is a deficient number, since it is larger than the sum of its proper divisors (820959).

1660221 is a wasteful number, since it uses less digits than its factorization.

1660221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6396 (or 6393 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 1660221 is about 1288.4956344513. The cubic root of 1660221 is about 118.4100690320.

Adding to 1660221 its reverse (1220661), we get a palindrome (2880882).

It can be divided in two parts, 1660 and 221, that added together give a palindrome (1881).

The spelling of 1660221 in words is "one million, six hundred sixty thousand, two hundred twenty-one".