81660280 has 64 divisors (see below), whose sum is σ = 201670560. Its totient is φ = 29572608.

The previous prime is 81660263. The next prime is 81660283. The reversal of 81660280 is 8206618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81660283) 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 15 ways as a sum of consecutive naturals, for example, 26079 + ... + 29041.

Almost surely, 2^81660280 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81660280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100835280).

81660280 is an abundant number, since it is smaller than the sum of its proper divisors (120010280).

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

81660280 is a wasteful number, since it uses less digits than its factorization.

81660280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3040 (or 3036 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 81660280 is about 9036.6077706184. The cubic root of 81660280 is about 433.8473558344.

Adding to 81660280 its reverse (8206618), we get a palindrome (89866898).

The spelling of 81660280 in words is "eighty-one million, six hundred sixty thousand, two hundred eighty".