78206518081 has 2 divisors, whose sum is σ = 78206518082. Its totient is φ = 78206518080.

The previous prime is 78206518069. The next prime is 78206518097. The reversal of 78206518081 is 18081560287.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61295856400 + 16910661681 = 247580^2 + 130041^2 .

It is a cyclic number.

It is not a de Polignac number, because 78206518081 - 2¹⁷ = 78206387009 is a prime.

It is a super-2 number, since 2×78206518081² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78206518781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39103259040 + 39103259041.

It is an arithmetic number, because the mean of its divisors is an integer number (39103259041).

Almost surely, 2^78206518081 is an apocalyptic number.

It is an amenable number.

78206518081 is a deficient number, since it is larger than the sum of its proper divisors (1).

78206518081 is an equidigital number, since it uses as much as digits as its factorization.

78206518081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 215040, while the sum is 46.

The spelling of 78206518081 in words is "seventy-eight billion, two hundred six million, five hundred eighteen thousand, eighty-one".