78839947 has 2 divisors, whose sum is σ = 78839948. Its totient is φ = 78839946.

The previous prime is 78839899. The next prime is 78839953. The reversal of 78839947 is 74993887.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78839947 is a prime.

It is not a weakly prime, because it can be changed into another prime (78839347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39419973 + 39419974.

It is an arithmetic number, because the mean of its divisors is an integer number (39419974).

Almost surely, 2^78839947 is an apocalyptic number.

78839947 is a deficient number, since it is larger than the sum of its proper divisors (1).

78839947 is an equidigital number, since it uses as much as digits as its factorization.

78839947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3048192, while the sum is 55.

The square root of 78839947 is about 8879.1861676620. The cubic root of 78839947 is about 428.7940738436.

The spelling of 78839947 in words is "seventy-eight million, eight hundred thirty-nine thousand, nine hundred forty-seven".