• 68 can be written using four 4's:

68 has 6 divisors (see below), whose sum is σ = 126. Its totient is φ = 32.

The previous prime is 67. The next prime is 71. The reversal of 68 is 86.

It is a happy number.

68 is nontrivially palindromic in base 3 and base 16.

68 is an esthetic number in base 4, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in only one way, i.e., 64 + 4 = 8^2 + 2^2 .

68 is an undulating number in base 4.

It is the 15-th Perrin number.

68 is a nontrivial repdigit in base 16.

It is a plaindrome in base 5, base 7, base 10, base 12, base 14, base 15 and base 16.

It is a nialpdrome in base 9, base 11, base 13 and base 16.

It is a zygodrome in base 16.

It is a pernicious number, because its binary representation contains a prime number (2) of ones.

In principle, a polygon with 68 sides can be constructed with ruler and compass.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5 + ... + 12.

It is an arithmetic number, because the mean of its divisors is an integer number (21).

It is an amenable number.

68 is a deficient number, since it is larger than the sum of its proper divisors (58).

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

68 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21 (or 19 counting only the distinct ones).

The product of its digits is 48, while the sum is 14.

The square root of 68 is about 8.2462112512. The cubic root of 68 is about 4.0816551019.

The spelling of 68 in words is "sixty-eight", and thus it is an aban number, an oban number, and an uban number.

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