81239760 has 280 divisors, whose sum is σ = 325276800. Its totient is φ = 18475776.

The previous prime is 81239713. The next prime is 81239761. The reversal of 81239760 is 6793218.

It is a tau number, because it is divible by the number of its divisors (280).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81239761) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 408141 + ... + 408339.

Almost surely, 2^81239760 is an apocalyptic number.

81239760 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 81239760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (162638400).

81239760 is an abundant number, since it is smaller than the sum of its proper divisors (244037040).

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

81239760 is a wasteful number, since it uses less digits than its factorization.

81239760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237 (or 216 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 81239760 is about 9013.3101577611. The cubic root of 81239760 is about 433.1013564425.

The spelling of 81239760 in words is "eighty-one million, two hundred thirty-nine thousand, seven hundred sixty".