6639555 has 32 divisors (see below), whose sum is σ = 11612160. Its totient is φ = 3219840.

The previous prime is 6639547. The next prime is 6639593. The reversal of 6639555 is 5559366.

It is not a de Polignac number, because 6639555 - 2³ = 6639547 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15190 + ... + 15620.

It is an arithmetic number, because the mean of its divisors is an integer number (362880).

Almost surely, 2^6639555 is an apocalyptic number.

6639555 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

6639555 is a deficient number, since it is larger than the sum of its proper divisors (4972605).

6639555 is a wasteful number, since it uses less digits than its factorization.

6639555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 531.

The product of its digits is 121500, while the sum is 39.

The square root of 6639555 is about 2576.7333971523. The cubic root of 6639555 is about 187.9517285906.

It can be divided in two parts, 66 and 39555, that added together give a triangular number (39621 = T₂₈₁).

The spelling of 6639555 in words is "six million, six hundred thirty-nine thousand, five hundred fifty-five".