81189144 has 96 divisors (see below), whose sum is σ = 235282320. Its totient is φ = 25202688.

The previous prime is 81189131. The next prime is 81189167. The reversal of 81189144 is 44198118.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 81189099 and 81189108.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 138019 + ... + 138605.

Almost surely, 2^81189144 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81189144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117641160).

81189144 is an abundant number, since it is smaller than the sum of its proper divisors (154093176).

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

81189144 is a wasteful number, since it uses less digits than its factorization.

81189144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 729 (or 722 counting only the distinct ones).

The product of its digits is 9216, while the sum is 36.

The square root of 81189144 is about 9010.5018728149. The cubic root of 81189144 is about 433.0113905908.

It can be divided in two parts, 81 and 189144, that added together give a square (189225 = 435²).

The spelling of 81189144 in words is "eighty-one million, one hundred eighty-nine thousand, one hundred forty-four".