81205800 has 192 divisors, whose sum is σ = 281232000. Its totient is φ = 19246080.

The previous prime is 81205799. The next prime is 81205811. The reversal of 81205800 is 850218.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 226021 + ... + 226379.

It is an arithmetic number, because the mean of its divisors is an integer number (1464750).

Almost surely, 2^81205800 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 81205800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140616000).

81205800 is an abundant number, since it is smaller than the sum of its proper divisors (200026200).

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

81205800 is a wasteful number, since it uses less digits than its factorization.

81205800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420 (or 411 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 24.

The square root of 81205800 is about 9011.4260802605. The cubic root of 81205800 is about 433.0409994122.

The spelling of 81205800 in words is "eighty-one million, two hundred five thousand, eight hundred".