81144140 has 48 divisors (see below), whose sum is σ = 212454144. Its totient is φ = 25291200.

The previous prime is 81144127. The next prime is 81144149. The reversal of 81144140 is 4144118.

It is not an unprimeable number, because it can be changed into a prime (81144149) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24806 + ... + 27885.

It is an arithmetic number, because the mean of its divisors is an integer number (4426128).

Almost surely, 2^81144140 is an apocalyptic number.

It is an amenable number.

81144140 is an abundant number, since it is smaller than the sum of its proper divisors (131310004).

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

81144140 is a wasteful number, since it uses less digits than its factorization.

81144140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52718 (or 52716 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 81144140 is about 9008.0042184715. The cubic root of 81144140 is about 432.9313682076.

Adding to 81144140 its reverse (4144118), we get a palindrome (85288258).

The spelling of 81144140 in words is "eighty-one million, one hundred forty-four thousand, one hundred forty".