78009109 has 2 divisors, whose sum is σ = 78009110. Its totient is φ = 78009108.

The previous prime is 78009091. The next prime is 78009119. The reversal of 78009109 is 90190087.

Together with previous prime (78009091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76912900 + 1096209 = 8770^2 + 1047^2 .

It is a cyclic number.

It is not a de Polignac number, because 78009109 - 2⁷ = 78008981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78009119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39004554 + 39004555.

It is an arithmetic number, because the mean of its divisors is an integer number (39004555).

Almost surely, 2^78009109 is an apocalyptic number.

It is an amenable number.

78009109 is a deficient number, since it is larger than the sum of its proper divisors (1).

78009109 is an equidigital number, since it uses as much as digits as its factorization.

78009109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 34.

The square root of 78009109 is about 8832.2765468479. The cubic root of 78009109 is about 427.2824998506.

The spelling of 78009109 in words is "seventy-eight million, nine thousand, one hundred nine".