68451781 has 2 divisors, whose sum is σ = 68451782. Its totient is φ = 68451780.

The previous prime is 68451731. The next prime is 68451811. The reversal of 68451781 is 18715486.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 63760225 + 4691556 = 7985^2 + 2166^2 .

It is a cyclic number.

It is not a de Polignac number, because 68451781 - 2¹³ = 68443589 is a prime.

It is a super-2 number, since 2×68451781² = 9371292644143922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (68451731) 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, 34225890 + 34225891.

It is an arithmetic number, because the mean of its divisors is an integer number (34225891).

Almost surely, 2^68451781 is an apocalyptic number.

It is an amenable number.

68451781 is a deficient number, since it is larger than the sum of its proper divisors (1).

68451781 is an equidigital number, since it uses as much as digits as its factorization.

68451781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 53760, while the sum is 40.

The square root of 68451781 is about 8273.5591494834. The cubic root of 68451781 is about 409.0674442374.

The spelling of 68451781 in words is "sixty-eight million, four hundred fifty-one thousand, seven hundred eighty-one".