78047909 has 2 divisors, whose sum is σ = 78047910. Its totient is φ = 78047908.

The previous prime is 78047897. The next prime is 78047923. The reversal of 78047909 is 90974087.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76300225 + 1747684 = 8735^2 + 1322^2 .

It is a cyclic number.

It is not a de Polignac number, because 78047909 - 2⁸ = 78047653 is a prime.

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 78047909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78047939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39023954 + 39023955.

It is an arithmetic number, because the mean of its divisors is an integer number (39023955).

Almost surely, 2^78047909 is an apocalyptic number.

It is an amenable number.

78047909 is a deficient number, since it is larger than the sum of its proper divisors (1).

78047909 is an equidigital number, since it uses as much as digits as its factorization.

78047909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 127008, while the sum is 44.

The square root of 78047909 is about 8834.4727629893. The cubic root of 78047909 is about 427.3533283874.

The spelling of 78047909 in words is "seventy-eight million, forty-seven thousand, nine hundred nine".