81518400 has 420 divisors, whose sum is σ = 325841868. Its totient is φ = 19906560.

The previous prime is 81518389. The next prime is 81518401. The reversal of 81518400 is 481518.

It can be written as a sum of positive squares in 6 ways, for example, as 4359744 + 77158656 = 2088^2 + 8784^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81518401) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 2203182 + ... + 2203218.

Almost surely, 2^81518400 is an apocalyptic number.

81518400 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 81518400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (162920934).

81518400 is an abundant number, since it is smaller than the sum of its proper divisors (244323468).

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

81518400 is a wasteful number, since it uses less digits than its factorization.

81518400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88 (or 64 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 81518400 is about 9028.7540668688. The cubic root of 81518400 is about 433.5959486375.

Adding to 81518400 its reverse (481518), we get a palindrome (81999918).

It can be divided in two parts, 81518 and 400, that added together give a palindrome (81918).

The spelling of 81518400 in words is "eighty-one million, five hundred eighteen thousand, four hundred".