78421966789 has 2 divisors, whose sum is σ = 78421966790. Its totient is φ = 78421966788.

The previous prime is 78421966771. The next prime is 78421966811. The reversal of 78421966789 is 98766912487.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72331413025 + 6090553764 = 268945^2 + 78042^2 .

It is a cyclic number.

It is not a de Polignac number, because 78421966789 - 2⁵ = 78421966757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78421961789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39210983394 + 39210983395.

It is an arithmetic number, because the mean of its divisors is an integer number (39210983395).

Almost surely, 2^78421966789 is an apocalyptic number.

It is an amenable number.

78421966789 is a deficient number, since it is larger than the sum of its proper divisors (1).

78421966789 is an equidigital number, since it uses as much as digits as its factorization.

78421966789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 73156608, while the sum is 67.

The spelling of 78421966789 in words is "seventy-eight billion, four hundred twenty-one million, nine hundred sixty-six thousand, seven hundred eighty-nine".