81855400 has 96 divisors (see below), whose sum is σ = 214941600. Its totient is φ = 28716800.

The previous prime is 81855377. The next prime is 81855419. The reversal of 81855400 is 455818.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 63159 + ... + 64441.

It is an arithmetic number, because the mean of its divisors is an integer number (2238975).

Almost surely, 2^81855400 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 81855400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107470800).

81855400 is an abundant number, since it is smaller than the sum of its proper divisors (133086200).

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

81855400 is a wasteful number, since it uses less digits than its factorization.

81855400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1339 (or 1330 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 31.

The square root of 81855400 is about 9047.3974158318. The cubic root of 81855400 is about 434.1926275805.

The spelling of 81855400 in words is "eighty-one million, eight hundred fifty-five thousand, four hundred".