81359280 has 240 divisors, whose sum is σ = 302927040. Its totient is φ = 19531776.

The previous prime is 81359251. The next prime is 81359281. The reversal of 81359280 is 8295318.

It is a tau number, because it is divible by the number of its divisors (240).

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

It is not an unprimeable number, because it can be changed into a prime (81359281) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 3537349 + ... + 3537371.

It is an arithmetic number, because the mean of its divisors is an integer number (1262196).

Almost surely, 2^81359280 is an apocalyptic number.

81359280 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 81359280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (151463520).

81359280 is an abundant number, since it is smaller than the sum of its proper divisors (221567760).

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

81359280 is a wasteful number, since it uses less digits than its factorization.

81359280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93 (or 50 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 81359280 is about 9019.9379155291. The cubic root of 81359280 is about 433.3136453909.

The spelling of 81359280 in words is "eighty-one million, three hundred fifty-nine thousand, two hundred eighty".