81550560 has 192 divisors, whose sum is σ = 316334592. Its totient is φ = 17197056.

The previous prime is 81550543. The next prime is 81550561. The reversal of 81550560 is 6505518.

It is a happy number.

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 (81550561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42747 + ... + 44613.

It is an arithmetic number, because the mean of its divisors is an integer number (1647576).

Almost surely, 2^81550560 is an apocalyptic number.

81550560 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 81550560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158167296).

81550560 is an abundant number, since it is smaller than the sum of its proper divisors (234784032).

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

81550560 is a wasteful number, since it uses less digits than its factorization.

81550560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1905 (or 1897 counting only the distinct ones).

The product of its (nonzero) digits is 6000, while the sum is 30.

The square root of 81550560 is about 9030.5348678802. The cubic root of 81550560 is about 433.6529607655.

The spelling of 81550560 in words is "eighty-one million, five hundred fifty thousand, five hundred sixty".