81389800 has 48 divisors (see below), whose sum is σ = 191550240. Its totient is φ = 32157120.

The previous prime is 81389779. The next prime is 81389807. The reversal of 81389800 is 898318.

It is a self number, because there is not a number n which added to its sum of digits gives 81389800.

It is not an unprimeable number, because it can be changed into a prime (81389807) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14149 + ... + 19051.

It is an arithmetic number, because the mean of its divisors is an integer number (3990630).

Almost surely, 2^81389800 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 81389800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95775120).

81389800 is an abundant number, since it is smaller than the sum of its proper divisors (110160440).

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

81389800 is a wasteful number, since it uses less digits than its factorization.

81389800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5002 (or 4993 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 37.

The square root of 81389800 is about 9021.6295645521. The cubic root of 81389800 is about 433.3678210553.

The spelling of 81389800 in words is "eighty-one million, three hundred eighty-nine thousand, eight hundred".