78643649993 has 2 divisors, whose sum is σ = 78643649994. Its totient is φ = 78643649992.

The previous prime is 78643649989. The next prime is 78643650011. The reversal of 78643649993 is 39994634687.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 56528391049 + 22115258944 = 237757^2 + 148712^2 .

It is a cyclic number.

It is not a de Polignac number, because 78643649993 - 2² = 78643649989 is a prime.

It is not a weakly prime, because it can be changed into another prime (78643649963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39321824996 + 39321824997.

It is an arithmetic number, because the mean of its divisors is an integer number (39321824997).

Almost surely, 2^78643649993 is an apocalyptic number.

It is an amenable number.

78643649993 is a deficient number, since it is larger than the sum of its proper divisors (1).

78643649993 is an equidigital number, since it uses as much as digits as its factorization.

78643649993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 211631616, while the sum is 68.

The spelling of 78643649993 in words is "seventy-eight billion, six hundred forty-three million, six hundred forty-nine thousand, nine hundred ninety-three".