81238140 has 60 divisors (see below), whose sum is σ = 254852136. Its totient is φ = 21663072.

The previous prime is 81238127. The next prime is 81238147. The reversal of 81238140 is 4183218.

It is a tau number, because it is divible by the number of its divisors (60).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81238147) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 23454 + ... + 26693.

Almost surely, 2^81238140 is an apocalyptic number.

It is an amenable number.

81238140 is an abundant number, since it is smaller than the sum of its proper divisors (173613996).

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

81238140 is a wasteful number, since it uses less digits than its factorization.

81238140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50168 (or 50157 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 81238140 is about 9013.2202902181. The cubic root of 81238140 is about 433.0984776023.

The spelling of 81238140 in words is "eighty-one million, two hundred thirty-eight thousand, one hundred forty".