78939761 has 2 divisors, whose sum is σ = 78939762. Its totient is φ = 78939760.

The previous prime is 78939697. The next prime is 78939779. The reversal of 78939761 is 16793987.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78872161 + 67600 = 8881^2 + 260^2 .

It is a cyclic number.

It is not a de Polignac number, because 78939761 - 2⁶ = 78939697 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (78939781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39469880 + 39469881.

It is an arithmetic number, because the mean of its divisors is an integer number (39469881).

Almost surely, 2^78939761 is an apocalyptic number.

It is an amenable number.

78939761 is a deficient number, since it is larger than the sum of its proper divisors (1).

78939761 is an equidigital number, since it uses as much as digits as its factorization.

78939761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 571536, while the sum is 50.

The square root of 78939761 is about 8884.8050625773. The cubic root of 78939761 is about 428.9749533938.

The spelling of 78939761 in words is "seventy-eight million, nine hundred thirty-nine thousand, seven hundred sixty-one".