81571740 has 24 divisors (see below), whose sum is σ = 228401040. Its totient is φ = 21752448.

The previous prime is 81571703. The next prime is 81571747. The reversal of 81571740 is 4717518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81571747) 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, 679705 + ... + 679824.

It is an arithmetic number, because the mean of its divisors is an integer number (9516710).

Almost surely, 2^81571740 is an apocalyptic number.

It is an amenable number.

81571740 is an abundant number, since it is smaller than the sum of its proper divisors (146829300).

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

81571740 is a wasteful number, since it uses less digits than its factorization.

81571740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1359541 (or 1359539 counting only the distinct ones).

The product of its (nonzero) digits is 7840, while the sum is 33.

The square root of 81571740 is about 9031.7074797626. The cubic root of 81571740 is about 433.6904997461.

The spelling of 81571740 in words is "eighty-one million, five hundred seventy-one thousand, seven hundred forty".