6687647281 has 4 divisors (see below), whose sum is σ = 7643025472. Its totient is φ = 5732269092.

The previous prime is 6687647269. The next prime is 6687647297. The reversal of 6687647281 is 1827467866.

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 not a de Polignac number, because 6687647281 - 2¹⁹ = 6687122993 is a prime.

It is a super-2 number, since 2×6687647281² = 89449252310133385922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6687647201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 477689085 + ... + 477689098.

It is an arithmetic number, because the mean of its divisors is an integer number (1910756368).

Almost surely, 2^6687647281 is an apocalyptic number.

It is an amenable number.

6687647281 is a deficient number, since it is larger than the sum of its proper divisors (955378191).

6687647281 is an equidigital number, since it uses as much as digits as its factorization.

6687647281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 955378190.

The product of its digits is 5419008, while the sum is 55.

The square root of 6687647281 is about 81778.0366663324. The cubic root of 6687647281 is about 1884.0443416200.

The spelling of 6687647281 in words is "six billion, six hundred eighty-seven million, six hundred forty-seven thousand, two hundred eighty-one".