81249120 has 144 divisors (see below), whose sum is σ = 293660640. Its totient is φ = 20385792.

The previous prime is 81249107. The next prime is 81249131. The reversal of 81249120 is 2194218.

It is a tau number, because it is divible by the number of its divisors (144).

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, 22821 + ... + 26139.

It is an arithmetic number, because the mean of its divisors is an integer number (2039310).

Almost surely, 2^81249120 is an apocalyptic number.

81249120 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 81249120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146830320).

81249120 is an abundant number, since it is smaller than the sum of its proper divisors (212411520).

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

81249120 is a wasteful number, since it uses less digits than its factorization.

81249120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3357 (or 3346 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 81249120 is about 9013.8293749105. The cubic root of 81249120 is about 433.1179889922.

The spelling of 81249120 in words is "eighty-one million, two hundred forty-nine thousand, one hundred twenty".