81812178 has 48 divisors (see below), whose sum is σ = 206421696. Its totient is φ = 22932000.

The previous prime is 81812167. The next prime is 81812183. The reversal of 81812178 is 87121818.

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, 553 + ... + 12803.

It is an arithmetic number, because the mean of its divisors is an integer number (4300452).

Almost surely, 2^81812178 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81812178, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103210848).

81812178 is an abundant number, since it is smaller than the sum of its proper divisors (124609518).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81812178 is a wasteful number, since it uses less digits than its factorization.

81812178 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12319 (or 12316 counting only the distinct ones).

The product of its digits is 7168, while the sum is 36.

The square root of 81812178 is about 9045.0084577075. The cubic root of 81812178 is about 434.1161920701.

It can be divided in two parts, 818 and 12178, that added together give a square (12996 = 114²).

The spelling of 81812178 in words is "eighty-one million, eight hundred twelve thousand, one hundred seventy-eight".