6639985279 has 4 divisors (see below), whose sum is σ = 6640512480. Its totient is φ = 6639458080.

The previous prime is 6639985267. The next prime is 6639985283. The reversal of 6639985279 is 9725899366.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6639985279 - 2⁷ = 6639985151 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6639985279.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6639935279) 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, 244234 + ... + 270055.

It is an arithmetic number, because the mean of its divisors is an integer number (1660128120).

Almost surely, 2^6639985279 is an apocalyptic number.

6639985279 is a deficient number, since it is larger than the sum of its proper divisors (527201).

6639985279 is a wasteful number, since it uses less digits than its factorization.

6639985279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527200.

The product of its digits is 44089920, while the sum is 64.

The square root of 6639985279 is about 81486.1048216197. The cubic root of 6639985279 is about 1879.5578859839.

The spelling of 6639985279 in words is "six billion, six hundred thirty-nine million, nine hundred eighty-five thousand, two hundred seventy-nine".