81001140 has 192 divisors, whose sum is σ = 264757248. Its totient is φ = 18316800.

The previous prime is 81001139. The next prime is 81001153. The reversal of 81001140 is 4110018.

It is a super-2 number, since 2×81001140² = 13122369362599200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 756967 + ... + 757073.

It is an arithmetic number, because the mean of its divisors is an integer number (1378944).

Almost surely, 2^81001140 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 81001140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132378624).

81001140 is an abundant number, since it is smaller than the sum of its proper divisors (183756108).

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

81001140 is a wasteful number, since it uses less digits than its factorization.

81001140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198 (or 196 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 81001140 is about 9000.0633331105. The cubic root of 81001140 is about 432.6769009154.

Adding to 81001140 its reverse (4110018), we get a palindrome (85111158).

The spelling of 81001140 in words is "eighty-one million, one thousand, one hundred forty".