78220819709 has 2 divisors, whose sum is σ = 78220819710. Its totient is φ = 78220819708.

The previous prime is 78220819619. The next prime is 78220819723. The reversal of 78220819709 is 90791802287.

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., 42684799609 + 35536020100 = 206603^2 + 188510^2 .

It is a cyclic number.

It is not a de Polignac number, because 78220819709 - 2²⁴ = 78204042493 is a prime.

It is a super-2 number, since 2×78220819709² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78220819739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39110409854 + 39110409855.

It is an arithmetic number, because the mean of its divisors is an integer number (39110409855).

Almost surely, 2^78220819709 is an apocalyptic number.

It is an amenable number.

78220819709 is a deficient number, since it is larger than the sum of its proper divisors (1).

78220819709 is an equidigital number, since it uses as much as digits as its factorization.

78220819709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1016064, while the sum is 53.

The spelling of 78220819709 in words is "seventy-eight billion, two hundred twenty million, eight hundred nineteen thousand, seven hundred nine".