6706638821 has 4 divisors (see below), whose sum is σ = 6849333312. Its totient is φ = 6563944332.

The previous prime is 6706638811. The next prime is 6706638853. The reversal of 6706638821 is 1288366076.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6706638821 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (47), and also a Moran number because the ratio is a prime number: 142694443 = 6706638821 / (6 + 7 + 0 + 6 + 6 + 3 + 8 + 8 + 2 + 1).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6706638811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71347175 + ... + 71347268.

It is an arithmetic number, because the mean of its divisors is an integer number (1712333328).

Almost surely, 2^6706638821 is an apocalyptic number.

It is an amenable number.

6706638821 is a deficient number, since it is larger than the sum of its proper divisors (142694491).

6706638821 is a wasteful number, since it uses less digits than its factorization.

6706638821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142694490.

The product of its (nonzero) digits is 580608, while the sum is 47.

The square root of 6706638821 is about 81894.0707316470. The cubic root of 6706638821 is about 1885.8260886319.

The spelling of 6706638821 in words is "six billion, seven hundred six million, six hundred thirty-eight thousand, eight hundred twenty-one".