81281535 has 16 divisors (see below), whose sum is σ = 134246400. Its totient is φ = 41951520.

The previous prime is 81281533. The next prime is 81281537. The reversal of 81281535 is 53518218.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81281533) and next prime (81281537).

It is not a de Polignac number, because 81281535 - 2¹ = 81281533 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81281496 and 81281505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81281531) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 86935 + ... + 87864.

It is an arithmetic number, because the mean of its divisors is an integer number (8390400).

Almost surely, 2^81281535 is an apocalyptic number.

81281535 is a deficient number, since it is larger than the sum of its proper divisors (52964865).

81281535 is a wasteful number, since it uses less digits than its factorization.

81281535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174838.

The product of its digits is 9600, while the sum is 33.

The square root of 81281535 is about 9015.6272660309. The cubic root of 81281535 is about 433.1755799871.

The spelling of 81281535 in words is "eighty-one million, two hundred eighty-one thousand, five hundred thirty-five".