81142560 has 144 divisors (see below), whose sum is σ = 287292096. Its totient is φ = 21627648.

The previous prime is 81142553. The next prime is 81142571. The reversal of 81142560 is 6524118.

It is a tau number, because it is divible by the number of its divisors (144).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 37837 + ... + 39923.

It is an arithmetic number, because the mean of its divisors is an integer number (1995084).

Almost surely, 2^81142560 is an apocalyptic number.

81142560 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 81142560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143646048).

81142560 is an abundant number, since it is smaller than the sum of its proper divisors (206149536).

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

81142560 is a wasteful number, since it uses less digits than its factorization.

81142560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2117 (or 2097 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 81142560 is about 9007.9165182633. The cubic root of 81142560 is about 432.9285582450.

Adding to 81142560 its reverse (6524118), we get a palindrome (87666678).

The spelling of 81142560 in words is "eighty-one million, one hundred forty-two thousand, five hundred sixty".