78155639059681 has 8 divisors (see below), whose sum is σ = 78849571178664. Its totient is φ = 77461747104000.

The previous prime is 78155639059679. The next prime is 78155639059703. The reversal of 78155639059681 is 18695093655187.

It can be written as a sum of positive squares in 4 ways, for example, as 13773309760081 + 64382329299600 = 3711241^2 + 8023860^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 78155639059681 - 2¹ = 78155639059679 is a prime.

It is a super-2 number, since 2×78155639059681² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78155639059601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6124906 + ... + 13922131.

It is an arithmetic number, because the mean of its divisors is an integer number (9856196397333).

Almost surely, 2^{78155639059681} is an apocalyptic number.

It is an amenable number.

78155639059681 is a deficient number, since it is larger than the sum of its proper divisors (693932118983).

78155639059681 is a wasteful number, since it uses less digits than its factorization.

78155639059681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20081651.

The product of its (nonzero) digits is 489888000, while the sum is 73.

The spelling of 78155639059681 in words is "seventy-eight trillion, one hundred fifty-five billion, six hundred thirty-nine million, fifty-nine thousand, six hundred eighty-one".