81218884178 has 8 divisors (see below), whose sum is σ = 121950524172. Its totient is φ = 40568709456.

The previous prime is 81218884129. The next prime is 81218884193. The reversal of 81218884178 is 87148881218.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 79480577929 + 1738306249 = 281923^2 + 41693^2 .

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, 20363825 + ... + 20367812.

Almost surely, 2^81218884178 is an apocalyptic number.

81218884178 is a deficient number, since it is larger than the sum of its proper divisors (40731639994).

81218884178 is a wasteful number, since it uses less digits than its factorization.

81218884178 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40732636.

The product of its digits is 1835008, while the sum is 56.

The spelling of 81218884178 in words is "eighty-one billion, two hundred eighteen million, eight hundred eighty-four thousand, one hundred seventy-eight".