81871240 has 32 divisors (see below), whose sum is σ = 200957760. Its totient is φ = 29771200.

The previous prime is 81871213. The next prime is 81871243. The reversal of 81871240 is 4217818.

It is not an unprimeable number, because it can be changed into a prime (81871243) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 92596 + ... + 93475.

It is an arithmetic number, because the mean of its divisors is an integer number (6279930).

Almost surely, 2^81871240 is an apocalyptic number.

It is an amenable number.

81871240 is an abundant number, since it is smaller than the sum of its proper divisors (119086520).

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

81871240 is a wasteful number, since it uses less digits than its factorization.

81871240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186093 (or 186089 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 81871240 is about 9048.2727633510. The cubic root of 81871240 is about 434.2206329315.

The spelling of 81871240 in words is "eighty-one million, eight hundred seventy-one thousand, two hundred forty".