77966809 has 2 divisors, whose sum is σ = 77966810. Its totient is φ = 77966808.

The previous prime is 77966737. The next prime is 77966813. The reversal of 77966809 is 90866977.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69672409 + 8294400 = 8347^2 + 2880^2 .

It is an emirp because it is prime and its reverse (90866977) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77966809 - 2¹⁵ = 77934041 is a prime.

It is not a weakly prime, because it can be changed into another prime (77961809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38983404 + 38983405.

It is an arithmetic number, because the mean of its divisors is an integer number (38983405).

Almost surely, 2^77966809 is an apocalyptic number.

It is an amenable number.

77966809 is a deficient number, since it is larger than the sum of its proper divisors (1).

77966809 is an equidigital number, since it uses as much as digits as its factorization.

77966809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1143072, while the sum is 52.

The square root of 77966809 is about 8829.8815960351. The cubic root of 77966809 is about 427.2052553774.

The spelling of 77966809 in words is "seventy-seven million, nine hundred sixty-six thousand, eight hundred nine".