81871040 has 28 divisors (see below), whose sum is σ = 194956176. Its totient is φ = 32748288.

The previous prime is 81871021. The next prime is 81871043. The reversal of 81871040 is 4017818.

It is a junction number, because it is equal to n+sod(n) for n = 81870994 and 81871012.

It is not an unprimeable number, because it can be changed into a prime (81871043) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 127604 + ... + 128243.

Almost surely, 2^81871040 is an apocalyptic number.

81871040 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81871040 is an abundant number, since it is smaller than the sum of its proper divisors (113085136).

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

81871040 is a wasteful number, since it uses less digits than its factorization.

81871040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255864 (or 255854 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 81871040 is about 9048.2617115112. The cubic root of 81871040 is about 434.2202793511.

Adding to 81871040 its reverse (4017818), we get a palindrome (85888858).

The spelling of 81871040 in words is "eighty-one million, eight hundred seventy-one thousand, forty".