81656480 has 96 divisors (see below), whose sum is σ = 202341888. Its totient is φ = 31104000.

The previous prime is 81656473. The next prime is 81656483. The reversal of 81656480 is 8465618.

It is a super-3 number, since 3×81656480³ (a number of 25 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (81656483) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 500879 + ... + 501041.

It is an arithmetic number, because the mean of its divisors is an integer number (2107728).

Almost surely, 2^81656480 is an apocalyptic number.

81656480 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 81656480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101170944).

81656480 is an abundant number, since it is smaller than the sum of its proper divisors (120685408).

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

81656480 is a wasteful number, since it uses less digits than its factorization.

81656480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310 (or 302 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 38.

The square root of 81656480 is about 9036.3975122833. The cubic root of 81656480 is about 433.8406261427.

The spelling of 81656480 in words is "eighty-one million, six hundred fifty-six thousand, four hundred eighty".