81117178478 has 48 divisors (see below), whose sum is σ = 149929281504. Its totient is φ = 32705971200.

The previous prime is 81117178463. The next prime is 81117178489. The reversal of 81117178478 is 87487171118.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4657775 + ... + 4675157.

It is an arithmetic number, because the mean of its divisors is an integer number (3123526698).

Almost surely, 2^81117178478 is an apocalyptic number.

81117178478 is a deficient number, since it is larger than the sum of its proper divisors (68812103026).

81117178478 is a wasteful number, since it uses less digits than its factorization.

81117178478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20217 (or 20210 counting only the distinct ones).

The product of its digits is 702464, while the sum is 53.

The spelling of 81117178478 in words is "eighty-one billion, one hundred seventeen million, one hundred seventy-eight thousand, four hundred seventy-eight".