81581360 has 40 divisors (see below), whose sum is σ = 216774816. Its totient is φ = 27970560.

The previous prime is 81581347. The next prime is 81581389. The reversal of 81581360 is 6318518.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 72281 + ... + 73400.

Almost surely, 2^81581360 is an apocalyptic number.

81581360 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81581360 is an abundant number, since it is smaller than the sum of its proper divisors (135193456).

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

81581360 is a wasteful number, since it uses less digits than its factorization.

81581360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145701 (or 145695 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 81581360 is about 9032.2400322401. The cubic root of 81581360 is about 433.7075478832.

Adding to 81581360 its reverse (6318518), we get a palindrome (87899878).

The spelling of 81581360 in words is "eighty-one million, five hundred eighty-one thousand, three hundred sixty".