6688888981 has 2 divisors, whose sum is σ = 6688888982. Its totient is φ = 6688888980.

The previous prime is 6688888963. The next prime is 6688889021. The reversal of 6688888981 is 1898888866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5127848881 + 1561040100 = 71609^2 + 39510^2 .

It is a cyclic number.

It is not a de Polignac number, because 6688888981 - 2¹³ = 6688880789 is a prime.

It is a super-2 number, since 2×6688888981² = 89482471600286436722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6688888981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6688888931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3344444490 + 3344444491.

It is an arithmetic number, because the mean of its divisors is an integer number (3344444491).

Almost surely, 2^6688888981 is an apocalyptic number.

It is an amenable number.

6688888981 is a deficient number, since it is larger than the sum of its proper divisors (1).

6688888981 is an equidigital number, since it uses as much as digits as its factorization.

6688888981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 84934656, while the sum is 70.

The square root of 6688888981 is about 81785.6282056939. The cubic root of 6688888981 is about 1884.1609383337.

The spelling of 6688888981 in words is "six billion, six hundred eighty-eight million, eight hundred eighty-eight thousand, nine hundred eighty-one".