1668181 has 6 divisors (see below), whose sum is σ = 1760982. Its totient is φ = 1580040.

The previous prime is 1668137. The next prime is 1668197. The reversal of 1668181 is 1818661.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1343281 + 324900 = 1159^2 + 570^2 .

It is not a de Polignac number, because 1668181 - 2⁷ = 1668053 is a prime.

It is a super-2 number, since 2×1668181² = 5565655697522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1668131) 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 5 ways as a sum of consecutive naturals, for example, 1950 + ... + 2671.

It is an arithmetic number, because the mean of its divisors is an integer number (293497).

2^1668181 is an apocalyptic number.

It is an amenable number.

1668181 is a deficient number, since it is larger than the sum of its proper divisors (92801).

1668181 is an equidigital number, since it uses as much as digits as its factorization.

1668181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4659 (or 4640 counting only the distinct ones).

The product of its digits is 2304, while the sum is 31.

The square root of 1668181 is about 1291.5808143512. The cubic root of 1668181 is about 118.5990080935.

It can be divided in two parts, 1668 and 181, that added together give a square (1849 = 43²).

The spelling of 1668181 in words is "one million, six hundred sixty-eight thousand, one hundred eighty-one".