81296280 has 192 divisors, whose sum is σ = 294840000. Its totient is φ = 19289088.

The previous prime is 81296221. The next prime is 81296287. The reversal of 81296280 is 8269218.

81296280 is a `hidden beast` number, since 8 + 1 + 29 + 628 + 0 = 666.

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 (81296287) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 135421 + ... + 136019.

It is an arithmetic number, because the mean of its divisors is an integer number (1535625).

Almost surely, 2^81296280 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81296280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147420000).

81296280 is an abundant number, since it is smaller than the sum of its proper divisors (213543720).

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

81296280 is a wasteful number, since it uses less digits than its factorization.

81296280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 658 (or 651 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 81296280 is about 9016.4449757097. Note that the first 3 decimals coincide. The cubic root of 81296280 is about 433.2017720274.

The spelling of 81296280 in words is "eighty-one million, two hundred ninety-six thousand, two hundred eighty".