81687777778618 has 8 divisors (see below), whose sum is σ = 133670909092320. Its totient is φ = 37130808081180.

The previous prime is 81687777778561. The next prime is 81687777778639.

81687777778618 is nontrivially palindromic in base 10.

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1856540404038 + ... + 1856540404081.

It is an arithmetic number, because the mean of its divisors is an integer number (16708863636540).

Almost surely, 2^{81687777778618} is an apocalyptic number.

81687777778618 is a deficient number, since it is larger than the sum of its proper divisors (51983131313702).

81687777778618 is a wasteful number, since it uses less digits than its factorization.

81687777778618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3713080808132.

The product of its digits is 17348050944, while the sum is 88.

The spelling of 81687777778618 in words is "eighty-one trillion, six hundred eighty-seven billion, seven hundred seventy-seven million, seven hundred seventy-eight thousand, six hundred eighteen".