81866036880 has 320 divisors, whose sum is σ = 287392320000. Its totient is φ = 21415477248.

The previous prime is 81866036851. The next prime is 81866036897. The reversal of 81866036880 is 8863066818.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 31377016 + ... + 31379624.

It is an arithmetic number, because the mean of its divisors is an integer number (898101000).

Almost surely, 2^81866036880 is an apocalyptic number.

81866036880 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 81866036880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143696160000).

81866036880 is an abundant number, since it is smaller than the sum of its proper divisors (205526283120).

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

81866036880 is a wasteful number, since it uses less digits than its factorization.

81866036880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2903 (or 2891 counting only the distinct ones).

The product of its (nonzero) digits is 2654208, while the sum is 54.

The spelling of 81866036880 in words is "eighty-one billion, eight hundred sixty-six million, thirty-six thousand, eight hundred eighty".