6639985281 has 4 divisors (see below), whose sum is σ = 8853313712. Its totient is φ = 4426656852.

The previous prime is 6639985267. The next prime is 6639985283. The reversal of 6639985281 is 1825899366.

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.

It is not a de Polignac number, because 6639985281 - 2¹⁵ = 6639952513 is a prime.

It is a super-2 number, since 2×6639985281² = 88178809063793297922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6639985283) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1106664211 + ... + 1106664216.

It is an arithmetic number, because the mean of its divisors is an integer number (2213328428).

Almost surely, 2^6639985281 is an apocalyptic number.

It is an amenable number.

6639985281 is a deficient number, since it is larger than the sum of its proper divisors (2213328431).

6639985281 is a wasteful number, since it uses less digits than its factorization.

6639985281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2213328430.

The product of its digits is 5598720, while the sum is 57.

The square root of 6639985281 is about 81486.1048338918. The cubic root of 6639985281 is about 1879.5578861727.

The spelling of 6639985281 in words is "six billion, six hundred thirty-nine million, nine hundred eighty-five thousand, two hundred eighty-one".