81307680 has 96 divisors (see below), whose sum is σ = 257572224. Its totient is φ = 21559296.

The previous prime is 81307679. The next prime is 81307729. The reversal of 81307680 is 8670318.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×81307680² = 13221877653964800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111477 + ... + 112203.

It is an arithmetic number, because the mean of its divisors is an integer number (2683044).

Almost surely, 2^81307680 is an apocalyptic number.

81307680 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 81307680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128786112).

81307680 is an abundant number, since it is smaller than the sum of its proper divisors (176264544).

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

81307680 is a wasteful number, since it uses less digits than its factorization.

81307680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 978 (or 970 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 81307680 is about 9017.0771317539. The cubic root of 81307680 is about 433.2220200609. Note that the first 3 decimals are identical.

Adding to 81307680 its reverse (8670318), we get a palindrome (89977998).

The spelling of 81307680 in words is "eighty-one million, three hundred seven thousand, six hundred eighty".