81538400 has 72 divisors (see below), whose sum is σ = 200377800. Its totient is φ = 32399360.

The previous prime is 81538399. The next prime is 81538403. The reversal of 81538400 is 483518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81538403) 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, 181376 + ... + 181824.

It is an arithmetic number, because the mean of its divisors is an integer number (2783025).

Almost surely, 2^81538400 is an apocalyptic number.

81538400 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 81538400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100188900).

81538400 is an abundant number, since it is smaller than the sum of its proper divisors (118839400).

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

81538400 is a wasteful number, since it uses less digits than its factorization.

81538400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 696 (or 683 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 29.

The square root of 81538400 is about 9029.8615714749. The cubic root of 81538400 is about 433.6314057035.

The spelling of 81538400 in words is "eighty-one million, five hundred thirty-eight thousand, four hundred".