78246809 has 2 divisors, whose sum is σ = 78246810. Its totient is φ = 78246808.

The previous prime is 78246787. The next prime is 78246811. The reversal of 78246809 is 90864287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56670784 + 21576025 = 7528^2 + 4645^2 .

It is a cyclic number.

It is not a de Polignac number, because 78246809 - 2¹² = 78242713 is a prime.

It is a super-2 number, since 2×78246809² = 12245126237364962, which contains 22 as substring.

Together with 78246811, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78246809.

It is not a weakly prime, because it can be changed into another prime (78246829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39123404 + 39123405.

It is an arithmetic number, because the mean of its divisors is an integer number (39123405).

Almost surely, 2^78246809 is an apocalyptic number.

It is an amenable number.

78246809 is a deficient number, since it is larger than the sum of its proper divisors (1).

78246809 is an equidigital number, since it uses as much as digits as its factorization.

78246809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 193536, while the sum is 44.

The square root of 78246809 is about 8845.7226386542. The cubic root of 78246809 is about 427.7160477906.

The spelling of 78246809 in words is "seventy-eight million, two hundred forty-six thousand, eight hundred nine".