81811120 has 20 divisors (see below), whose sum is σ = 190211040. Its totient is φ = 32724416.

The previous prime is 81811109. The next prime is 81811141. The reversal of 81811120 is 2111818.

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 81811091 and 81811100.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 511240 + ... + 511399.

It is an arithmetic number, because the mean of its divisors is an integer number (9510552).

Almost surely, 2^81811120 is an apocalyptic number.

81811120 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81811120 is an abundant number, since it is smaller than the sum of its proper divisors (108399920).

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

81811120 is a wasteful number, since it uses less digits than its factorization.

81811120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1022652 (or 1022646 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 22.

The square root of 81811120 is about 9044.9499722221. The cubic root of 81811120 is about 434.1143207231.

Adding to 81811120 its reverse (2111818), we get a palindrome (83922938).

The spelling of 81811120 in words is "eighty-one million, eight hundred eleven thousand, one hundred twenty".