6668581 has 4 divisors (see below), whose sum is σ = 6777964. Its totient is φ = 6559200.

The previous prime is 6668567. The next prime is 6668603. The reversal of 6668581 is 1858666.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1858666 = 2 ⋅929333.

It can be written as a sum of positive squares in 2 ways, for example, as 1221025 + 5447556 = 1105^2 + 2334^2 .

It is a cyclic number.

It is not a de Polignac number, because 6668581 - 2⁵ = 6668549 is a prime.

It is a super-2 number, since 2×6668581² = 88939945107122, 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 (6668531) 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, 54600 + ... + 54721.

It is an arithmetic number, because the mean of its divisors is an integer number (1694491).

Almost surely, 2^6668581 is an apocalyptic number.

6668581 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

6668581 is a deficient number, since it is larger than the sum of its proper divisors (109383).

6668581 is a wasteful number, since it uses less digits than its factorization.

6668581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109382.

The product of its digits is 69120, while the sum is 40.

The square root of 6668581 is about 2582.3595799191. The cubic root of 6668581 is about 188.2252186186.

It can be divided in two parts, 66685 and 81, that added together give a palindrome (66766).

The spelling of 6668581 in words is "six million, six hundred sixty-eight thousand, five hundred eighty-one".