68257781 has 2 divisors, whose sum is σ = 68257782. Its totient is φ = 68257780.

The previous prime is 68257759. The next prime is 68257807. The reversal of 68257781 is 18775286.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63123025 + 5134756 = 7945^2 + 2266^2 .

It is a cyclic number.

It is not a de Polignac number, because 68257781 - 2²² = 64063477 is a prime.

It is a super-2 number, since 2×68257781² = 9318249334087922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a zygodrome in base 5.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (68257741) 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, 34128890 + 34128891.

It is an arithmetic number, because the mean of its divisors is an integer number (34128891).

Almost surely, 2^68257781 is an apocalyptic number.

It is an amenable number.

68257781 is a deficient number, since it is larger than the sum of its proper divisors (1).

68257781 is an equidigital number, since it uses as much as digits as its factorization.

68257781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 188160, while the sum is 44.

The square root of 68257781 is about 8261.8267350508. The cubic root of 68257781 is about 408.6806309598.

The spelling of 68257781 in words is "sixty-eight million, two hundred fifty-seven thousand, seven hundred eighty-one".