6645181 has 4 divisors (see below), whose sum is σ = 7036092. Its totient is φ = 6254272.

The previous prime is 6645169. The next prime is 6645187. The reversal of 6645181 is 1815466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1815466 = 2 ⋅907733.

It can be written as a sum of positive squares in 2 ways, for example, as 2277081 + 4368100 = 1509^2 + 2090^2 .

It is a cyclic number.

It is not a de Polignac number, because 6645181 - 2¹³ = 6636989 is a prime.

It is a super-2 number, since 2×6645181² = 88316861045522, 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 (6645187) 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, 195430 + ... + 195463.

It is an arithmetic number, because the mean of its divisors is an integer number (1759023).

Almost surely, 2^6645181 is an apocalyptic number.

It is an amenable number.

6645181 is a deficient number, since it is larger than the sum of its proper divisors (390911).

6645181 is a wasteful number, since it uses less digits than its factorization.

6645181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390910.

The product of its digits is 5760, while the sum is 31.

The square root of 6645181 is about 2577.8248582865. The cubic root of 6645181 is about 188.0048003150.

The spelling of 6645181 in words is "six million, six hundred forty-five thousand, one hundred eighty-one".