78826665358561 has 2 divisors, whose sum is σ = 78826665358562. Its totient is φ = 78826665358560.

The previous prime is 78826665358549. The next prime is 78826665358607. The reversal of 78826665358561 is 16585356662887.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 71411288270400 + 7415377088161 = 8450520^2 + 2723119^2 .

It is a cyclic number.

It is not a de Polignac number, because 78826665358561 - 2¹¹ = 78826665356513 is a prime.

It is not a weakly prime, because it can be changed into another prime (78826665358531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39413332679280 + 39413332679281.

It is an arithmetic number, because the mean of its divisors is an integer number (39413332679281).

Almost surely, 2^{78826665358561} is an apocalyptic number.

It is an amenable number.

78826665358561 is a deficient number, since it is larger than the sum of its proper divisors (1).

78826665358561 is an equidigital number, since it uses as much as digits as its factorization.

78826665358561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3483648000, while the sum is 76.

The spelling of 78826665358561 in words is "seventy-eight trillion, eight hundred twenty-six billion, six hundred sixty-five million, three hundred fifty-eight thousand, five hundred sixty-one".