78341635681 has 4 divisors (see below), whose sum is σ = 78461608212. Its totient is φ = 78221663152.

The previous prime is 78341635663. The next prime is 78341635717. The reversal of 78341635681 is 18653614387.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18653614387 = 6869 ⋅2715623.

It can be written as a sum of positive squares in 2 ways, for example, as 24907152400 + 53434483281 = 157820^2 + 231159^2 .

It is a cyclic number.

It is not a de Polignac number, because 78341635681 - 2¹⁷ = 78341504609 is a prime.

It is a super-2 number, since 2×78341635681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78341635661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 59985286 + ... + 59986591.

It is an arithmetic number, because the mean of its divisors is an integer number (19615402053).

Almost surely, 2^78341635681 is an apocalyptic number.

It is an amenable number.

78341635681 is a deficient number, since it is larger than the sum of its proper divisors (119972531).

78341635681 is a wasteful number, since it uses less digits than its factorization.

78341635681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119972530.

The product of its digits is 2903040, while the sum is 52.

The spelling of 78341635681 in words is "seventy-eight billion, three hundred forty-one million, six hundred thirty-five thousand, six hundred eighty-one".