68666681 has 2 divisors, whose sum is σ = 68666682. Its totient is φ = 68666680.

The previous prime is 68666651. The next prime is 68666683. The reversal of 68666681 is 18666686.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68624656 + 42025 = 8284^2 + 205^2 .

It is a cyclic number.

It is not a de Polignac number, because 68666681 - 2¹⁴ = 68650297 is a prime.

It is a super-2 number, since 2×68666681² = 9430226159111522, which contains 22 as substring.

Together with 68666683, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (68666683) 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 as a sum of consecutive naturals, namely, 34333340 + 34333341.

It is an arithmetic number, because the mean of its divisors is an integer number (34333341).

Almost surely, 2^68666681 is an apocalyptic number.

It is an amenable number.

68666681 is a deficient number, since it is larger than the sum of its proper divisors (1).

68666681 is an equidigital number, since it uses as much as digits as its factorization.

68666681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 497664, while the sum is 47.

The square root of 68666681 is about 8286.5361279608. The cubic root of 68666681 is about 409.4950774225.

The spelling of 68666681 in words is "sixty-eight million, six hundred sixty-six thousand, six hundred eighty-one".