78718421 has 2 divisors, whose sum is σ = 78718422. Its totient is φ = 78718420.

The previous prime is 78718363. The next prime is 78718427. The reversal of 78718421 is 12481787.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 43375396 + 35343025 = 6586^2 + 5945^2 .

It is an emirp because it is prime and its reverse (12481787) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78718421 - 2⁶ = 78718357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78718427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39359210 + 39359211.

It is an arithmetic number, because the mean of its divisors is an integer number (39359211).

Almost surely, 2^78718421 is an apocalyptic number.

It is an amenable number.

78718421 is a deficient number, since it is larger than the sum of its proper divisors (1).

78718421 is an equidigital number, since it uses as much as digits as its factorization.

78718421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25088, while the sum is 38.

The square root of 78718421 is about 8872.3402211592. The cubic root of 78718421 is about 428.5736423325.

The spelling of 78718421 in words is "seventy-eight million, seven hundred eighteen thousand, four hundred twenty-one".