78668641 has 2 divisors, whose sum is σ = 78668642. Its totient is φ = 78668640.

The previous prime is 78668621. The next prime is 78668657. The reversal of 78668641 is 14686687.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60902416 + 17766225 = 7804^2 + 4215^2 .

It is an emirp because it is prime and its reverse (14686687) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78668641 - 2⁵ = 78668609 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 78668591 and 78668600.

It is not a weakly prime, because it can be changed into another prime (78668621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39334320 + 39334321.

It is an arithmetic number, because the mean of its divisors is an integer number (39334321).

Almost surely, 2^78668641 is an apocalyptic number.

It is an amenable number.

78668641 is a deficient number, since it is larger than the sum of its proper divisors (1).

78668641 is an equidigital number, since it uses as much as digits as its factorization.

78668641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 387072, while the sum is 46.

The square root of 78668641 is about 8869.5344297206. The cubic root of 78668641 is about 428.4832827344.

The spelling of 78668641 in words is "seventy-eight million, six hundred sixty-eight thousand, six hundred forty-one".