81285029280 has 960 divisors, whose sum is σ = 356127045120. Its totient is φ = 17002192896.

The previous prime is 81285029279. The next prime is 81285029281. The reversal of 81285029280 is 8292058218.

81285029280 is a `hidden beast` number, since 8 + 1 + 285 + 0 + 292 + 80 = 666.

It is an interprime number because it is at equal distance from previous prime (81285029279) and next prime (81285029281).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (81285029281) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 185159301 + ... + 185159739.

It is an arithmetic number, because the mean of its divisors is an integer number (370965672).

Almost surely, 2^81285029280 is an apocalyptic number.

81285029280 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 81285029280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (178063522560).

81285029280 is an abundant number, since it is smaller than the sum of its proper divisors (274842015840).

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

81285029280 is a wasteful number, since it uses less digits than its factorization.

81285029280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643 (or 626 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 45.

The spelling of 81285029280 in words is "eighty-one billion, two hundred eighty-five million, twenty-nine thousand, two hundred eighty".