81930240 has 288 divisors, whose sum is σ = 327075840. Its totient is φ = 18579456.

The previous prime is 81930239. The next prime is 81930253. The reversal of 81930240 is 4203918.

It is a tau number, because it is divible by the number of its divisors (288).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 645057 + ... + 645183.

It is an arithmetic number, because the mean of its divisors is an integer number (1135680).

Almost surely, 2^81930240 is an apocalyptic number.

81930240 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 81930240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (163537920).

81930240 is an abundant number, since it is smaller than the sum of its proper divisors (245145600).

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

81930240 is a wasteful number, since it uses less digits than its factorization.

81930240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167 (or 144 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 81930240 is about 9051.5324669362. The cubic root of 81930240 is about 434.3249140187.

The spelling of 81930240 in words is "eighty-one million, nine hundred thirty thousand, two hundred forty".