78763781 has 2 divisors, whose sum is σ = 78763782. Its totient is φ = 78763780.

The previous prime is 78763733. The next prime is 78763801. The reversal of 78763781 is 18736787.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71656225 + 7107556 = 8465^2 + 2666^2 .

It is an emirp because it is prime and its reverse (18736787) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78763781 - 2⁶ = 78763717 is a prime.

It is a super-2 number, since 2×78763781² = 12407466394831922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78763481) 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, 39381890 + 39381891.

It is an arithmetic number, because the mean of its divisors is an integer number (39381891).

Almost surely, 2^78763781 is an apocalyptic number.

It is an amenable number.

78763781 is a deficient number, since it is larger than the sum of its proper divisors (1).

78763781 is an equidigital number, since it uses as much as digits as its factorization.

78763781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 395136, while the sum is 47.

The square root of 78763781 is about 8874.8961120680. The cubic root of 78763781 is about 428.6559456755.

The spelling of 78763781 in words is "seventy-eight million, seven hundred sixty-three thousand, seven hundred eighty-one".