78520109 has 2 divisors, whose sum is σ = 78520110. Its totient is φ = 78520108.

The previous prime is 78520097. The next prime is 78520129. The reversal of 78520109 is 90102587.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70930084 + 7590025 = 8422^2 + 2755^2 .

It is a cyclic number.

It is not a de Polignac number, because 78520109 - 2⁸ = 78519853 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78520129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39260054 + 39260055.

It is an arithmetic number, because the mean of its divisors is an integer number (39260055).

Almost surely, 2^78520109 is an apocalyptic number.

It is an amenable number.

78520109 is a deficient number, since it is larger than the sum of its proper divisors (1).

78520109 is an equidigital number, since it uses as much as digits as its factorization.

78520109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5040, while the sum is 32.

The square root of 78520109 is about 8861.1573171906. The cubic root of 78520109 is about 428.2134438478.

The spelling of 78520109 in words is "seventy-eight million, five hundred twenty thousand, one hundred nine".