81018140 has 24 divisors (see below), whose sum is σ = 194443872. Its totient is φ = 27777600.

The previous prime is 81018131. The next prime is 81018163. The reversal of 81018140 is 4181018.

It is a congruent number.

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, 289211 + ... + 289490.

It is an arithmetic number, because the mean of its divisors is an integer number (8101828).

Almost surely, 2^81018140 is an apocalyptic number.

It is an amenable number.

81018140 is an abundant number, since it is smaller than the sum of its proper divisors (113425732).

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

81018140 is a wasteful number, since it uses less digits than its factorization.

81018140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 578717 (or 578715 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 23.

The square root of 81018140 is about 9001.0077213610. The cubic root of 81018140 is about 432.7071679495.

Adding to 81018140 its reverse (4181018), we get a palindrome (85199158).

The spelling of 81018140 in words is "eighty-one million, eighteen thousand, one hundred forty".