6639181 has 4 divisors (see below), whose sum is σ = 6667200. Its totient is φ = 6611164.

The previous prime is 6639119. The next prime is 6639209. The reversal of 6639181 is 1819366.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1819366 = 2 ⋅909683.

It is a cyclic number.

It is not a de Polignac number, because 6639181 - 2⁹ = 6638669 is a prime.

It is a super-2 number, since 2×6639181² = 88157448701522, 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 (6639481) 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, 13651 + ... + 14128.

It is an arithmetic number, because the mean of its divisors is an integer number (1666800).

Almost surely, 2^6639181 is an apocalyptic number.

It is an amenable number.

6639181 is a deficient number, since it is larger than the sum of its proper divisors (28019).

6639181 is a wasteful number, since it uses less digits than its factorization.

6639181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28018.

The product of its digits is 7776, while the sum is 34.

The square root of 6639181 is about 2576.6608236243. The cubic root of 6639181 is about 187.9481994753.

The spelling of 6639181 in words is "six million, six hundred thirty-nine thousand, one hundred eighty-one".