81583281 has 20 divisors (see below), whose sum is σ = 131247732. Its totient is φ = 50204448.

The previous prime is 81583279. The next prime is 81583297. The reversal of 81583281 is 18238518.

It can be written as a sum of positive squares in 2 ways, for example, as 42458256 + 39125025 = 6516^2 + 6255^2 .

It is not a de Polignac number, because 81583281 - 2¹ = 81583279 is a prime.

It is a super-2 number, since 2×81583281² = 13311663477449922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81583181) 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, 37686 + ... + 39791.

Almost surely, 2^81583281 is an apocalyptic number.

81583281 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

81583281 is a deficient number, since it is larger than the sum of its proper divisors (49664451).

81583281 is a wasteful number, since it uses less digits than its factorization.

81583281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77502 (or 77493 counting only the distinct ones).

The product of its digits is 15360, while the sum is 36.

The square root of 81583281 is about 9032.3463728978. The cubic root of 81583281 is about 433.7109520336.

The spelling of 81583281 in words is "eighty-one million, five hundred eighty-three thousand, two hundred eighty-one".