81281660 has 12 divisors (see below), whose sum is σ = 170691528. Its totient is φ = 32512656.

The previous prime is 81281657. The next prime is 81281671. The reversal of 81281660 is 6618218.

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2032022 + ... + 2032061.

It is an arithmetic number, because the mean of its divisors is an integer number (14224294).

Almost surely, 2^81281660 is an apocalyptic number.

It is an amenable number.

81281660 is an abundant number, since it is smaller than the sum of its proper divisors (89409868).

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

81281660 is a wasteful number, since it uses less digits than its factorization.

81281660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4064092 (or 4064090 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 81281660 is about 9015.6341984355. The cubic root of 81281660 is about 433.1758020421.

Adding to 81281660 its reverse (6618218), we get a palindrome (87899878).

The spelling of 81281660 in words is "eighty-one million, two hundred eighty-one thousand, six hundred sixty".