81571280 has 60 divisors (see below), whose sum is σ = 220627620. Its totient is φ = 27965952.

The previous prime is 81571247. The next prime is 81571283. The reversal of 81571280 is 8217518.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 24840256 + 56731024 = 4984^2 + 7532^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81571283) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6485 + ... + 14324.

It is an arithmetic number, because the mean of its divisors is an integer number (3677127).

Almost surely, 2^81571280 is an apocalyptic number.

81571280 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81571280 is an abundant number, since it is smaller than the sum of its proper divisors (139056340).

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

81571280 is a wasteful number, since it uses less digits than its factorization.

81571280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20836 (or 20823 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 81571280 is about 9031.6820138887. The cubic root of 81571280 is about 433.6896845210.

Adding to 81571280 its reverse (8217518), we get a palindrome (89788798).

The spelling of 81571280 in words is "eighty-one million, five hundred seventy-one thousand, two hundred eighty".