77978839 has 2 divisors, whose sum is σ = 77978840. Its totient is φ = 77978838.

The previous prime is 77978827. The next prime is 77978897. The reversal of 77978839 is 93887977.

It is a happy number.

It is an a-pointer prime, because the next prime (77978897) can be obtained adding 77978839 to its sum of digits (58).

It is a weak prime.

It is an emirp because it is prime and its reverse (93887977) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77978839 - 2⁵ = 77978807 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77978039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38989419 + 38989420.

It is an arithmetic number, because the mean of its divisors is an integer number (38989420).

Almost surely, 2^77978839 is an apocalyptic number.

77978839 is a deficient number, since it is larger than the sum of its proper divisors (1).

77978839 is an equidigital number, since it uses as much as digits as its factorization.

77978839 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5334336, while the sum is 58.

The square root of 77978839 is about 8830.5627793476. The cubic root of 77978839 is about 427.2272263288.

The spelling of 77978839 in words is "seventy-seven million, nine hundred seventy-eight thousand, eight hundred thirty-nine".