81085680 has 120 divisors (see below), whose sum is σ = 293293728. Its totient is φ = 19957248.

The previous prime is 81085663. The next prime is 81085709. The reversal of 81085680 is 8658018.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5029 + ... + 13691.

Almost surely, 2^81085680 is an apocalyptic number.

81085680 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 81085680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146646864).

81085680 is an abundant number, since it is smaller than the sum of its proper divisors (212208048).

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

81085680 is a wasteful number, since it uses less digits than its factorization.

81085680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8695 (or 8686 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 36.

The square root of 81085680 is about 9004.7587419097. The cubic root of 81085680 is about 432.8273752876.

The spelling of 81085680 in words is "eighty-one million, eighty-five thousand, six hundred eighty".