81223680 has 112 divisors (see below), whose sum is σ = 260293104. Its totient is φ = 21626880.

The previous prime is 81223663. The next prime is 81223687. The reversal of 81223680 is 8632218.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81223687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 122550 + ... + 123210.

Almost surely, 2^81223680 is an apocalyptic number.

81223680 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 81223680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130146552).

81223680 is an abundant number, since it is smaller than the sum of its proper divisors (179069424).

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

81223680 is an equidigital number, since it uses as much as digits as its factorization.

81223680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695 (or 671 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 81223680 is about 9012.4180994892. The cubic root of 81223680 is about 433.0727795924.

Adding to 81223680 its reverse (8632218), we get a palindrome (89855898).

The spelling of 81223680 in words is "eighty-one million, two hundred twenty-three thousand, six hundred eighty".