6687657781 has 8 divisors (see below), whose sum is σ = 7906590720. Its totient is φ = 5534613168.

The previous prime is 6687657751. The next prime is 6687657793. The reversal of 6687657781 is 1877567866.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 6687657781 - 2⁵ = 6687657749 is a prime.

It is a super-2 number, since 2×6687657781² = 89449533191539687922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6687657701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16471861 + ... + 16472266.

It is an arithmetic number, because the mean of its divisors is an integer number (988323840).

Almost surely, 2^6687657781 is an apocalyptic number.

It is an amenable number.

6687657781 is a deficient number, since it is larger than the sum of its proper divisors (1218932939).

6687657781 is a wasteful number, since it uses less digits than its factorization.

6687657781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32944163.

The product of its digits is 23708160, while the sum is 61.

The square root of 6687657781 is about 81778.1008644735. The cubic root of 6687657781 is about 1884.0453276396.

The spelling of 6687657781 in words is "six billion, six hundred eighty-seven million, six hundred fifty-seven thousand, seven hundred eighty-one".