81216000 has 320 divisors, whose sum is σ = 306408960. Its totient is φ = 21196800.

The previous prime is 81215983. The next prime is 81216011. The reversal of 81216000 is 61218.

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1727977 + ... + 1728023.

It is an arithmetic number, because the mean of its divisors is an integer number (957528).

Almost surely, 2^81216000 is an apocalyptic number.

81216000 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 81216000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (153204480).

81216000 is an abundant number, since it is smaller than the sum of its proper divisors (225192960).

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

81216000 is an equidigital number, since it uses as much as digits as its factorization.

81216000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89 (or 57 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 81216000 is about 9011.9920106489. The cubic root of 81216000 is about 433.0591296166.

Adding to 81216000 its reverse (61218), we get a palindrome (81277218).

The spelling of 81216000 in words is "eighty-one million, two hundred sixteen thousand".