6639856155 has 12 divisors (see below), whose sum is σ = 11509084080. Its totient is φ = 3541256592.

The previous prime is 6639856121. The next prime is 6639856163. The reversal of 6639856155 is 5516589366.

It is a happy number.

It is not a de Polignac number, because 6639856155 - 2⁸ = 6639855899 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 73776135 + ... + 73776224.

It is an arithmetic number, because the mean of its divisors is an integer number (959090340).

Almost surely, 2^6639856155 is an apocalyptic number.

6639856155 is a deficient number, since it is larger than the sum of its proper divisors (4869227925).

6639856155 is a wasteful number, since it uses less digits than its factorization.

6639856155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147552370 (or 147552367 counting only the distinct ones).

The product of its digits is 5832000, while the sum is 54.

The square root of 6639856155 is about 81485.3125109059. The cubic root of 6639856155 is about 1879.5457023422.

The spelling of 6639856155 in words is "six billion, six hundred thirty-nine million, eight hundred fifty-six thousand, one hundred fifty-five".