76686721 has 2 divisors, whose sum is σ = 76686722. Its totient is φ = 76686720.

The previous prime is 76686713. The next prime is 76686733. The reversal of 76686721 is 12768667.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43046721 + 33640000 = 6561^2 + 5800^2 .

It is an emirp because it is prime and its reverse (12768667) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 76686721 - 2³ = 76686713 is a prime.

It is not a weakly prime, because it can be changed into another prime (76681721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38343360 + 38343361.

It is an arithmetic number, because the mean of its divisors is an integer number (38343361).

Almost surely, 2^76686721 is an apocalyptic number.

It is an amenable number.

76686721 is a deficient number, since it is larger than the sum of its proper divisors (1).

76686721 is an equidigital number, since it uses as much as digits as its factorization.

76686721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 169344, while the sum is 43.

The square root of 76686721 is about 8757.0954659636. The cubic root of 76686721 is about 424.8543371637.

It can be divided in two parts, 7668 and 6721, that multiplied together give a triangular number (51536628 = T₁₀₁₅₂).

The spelling of 76686721 in words is "seventy-six million, six hundred eighty-six thousand, seven hundred twenty-one".