6639918 has 8 divisors (see below), whose sum is σ = 13279848. Its totient is φ = 2213304.

The previous prime is 6639907. The next prime is 6639929. The reversal of 6639918 is 8199366.

It is an interprime number because it is at equal distance from previous prime (6639907) and next prime (6639929).

It is a sphenic number, since it is the product of 3 distinct primes.

6639918 is an admirable number.

It is a super-2 number, since 2×6639918² = 88177022093448, which contains 22 as substring.

It is an Ulam number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 6639918.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 553321 + ... + 553332.

It is an arithmetic number, because the mean of its divisors is an integer number (1659981).

Almost surely, 2^6639918 is an apocalyptic number.

6639918 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6639918 is a wasteful number, since it uses less digits than its factorization.

6639918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1106658.

The product of its digits is 69984, while the sum is 42.

The square root of 6639918 is about 2576.8038342101. The cubic root of 6639918 is about 187.9551537817.

It can be divided in two parts, 6639 and 918, that added together give a palindrome (7557).

The spelling of 6639918 in words is "six million, six hundred thirty-nine thousand, nine hundred eighteen".