81119920 has 80 divisors (see below), whose sum is σ = 228253248. Its totient is φ = 26173440.

The previous prime is 81119917. The next prime is 81119933. The reversal of 81119920 is 2991118.

It is a tau number, because it is divible by the number of its divisors (80).

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 15 ways as a sum of consecutive naturals, for example, 5260 + ... + 13780.

Almost surely, 2^81119920 is an apocalyptic number.

81119920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81119920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114126624).

81119920 is an abundant number, since it is smaller than the sum of its proper divisors (147133328).

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

81119920 is a wasteful number, since it uses less digits than its factorization.

81119920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8558 (or 8552 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 31.

The square root of 81119920 is about 9006.6597582012. The cubic root of 81119920 is about 432.8882899637. Note that the first 3 decimals are identical.

The spelling of 81119920 in words is "eighty-one million, one hundred nineteen thousand, nine hundred twenty".