78742109 has 2 divisors, whose sum is σ = 78742110. Its totient is φ = 78742108.

The previous prime is 78742093. The next prime is 78742151. The reversal of 78742109 is 90124787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70930084 + 7812025 = 8422^2 + 2795^2 .

It is a cyclic number.

It is not a de Polignac number, because 78742109 - 2⁴ = 78742093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78742189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39371054 + 39371055.

It is an arithmetic number, because the mean of its divisors is an integer number (39371055).

Almost surely, 2^78742109 is an apocalyptic number.

It is an amenable number.

78742109 is a deficient number, since it is larger than the sum of its proper divisors (1).

78742109 is an equidigital number, since it uses as much as digits as its factorization.

78742109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 78742109 is about 8873.6750560295. The cubic root of 78742109 is about 428.6166269103.

The spelling of 78742109 in words is "seventy-eight million, seven hundred forty-two thousand, one hundred nine".