81400140 has 96 divisors (see below), whose sum is σ = 256509120. Its totient is φ = 21695040.

The previous prime is 81400093. The next prime is 81400171. The reversal of 81400140 is 4100418.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42810 + ... + 44670.

It is an arithmetic number, because the mean of its divisors is an integer number (2671970).

Almost surely, 2^81400140 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 81400140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128254560).

81400140 is an abundant number, since it is smaller than the sum of its proper divisors (175108980).

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

81400140 is a wasteful number, since it uses less digits than its factorization.

81400140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1891 (or 1871 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 81400140 is about 9022.2026135529. The cubic root of 81400140 is about 433.3861723865.

Adding to 81400140 its reverse (4100418), we get a palindrome (85500558).

The spelling of 81400140 in words is "eighty-one million, four hundred thousand, one hundred forty".