81834561 has 12 divisors (see below), whose sum is σ = 118405092. Its totient is φ = 54464256.

The previous prime is 81834559. The next prime is 81834581. The reversal of 81834561 is 16543818.

It can be written as a sum of positive squares in 2 ways, for example, as 31708161 + 50126400 = 5631^2 + 7080^2 .

It is not a de Polignac number, because 81834561 - 2¹ = 81834559 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81834551) 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, 1816 + ... + 12921.

It is an arithmetic number, because the mean of its divisors is an integer number (9867091).

Almost surely, 2^81834561 is an apocalyptic number.

It is an amenable number.

81834561 is a deficient number, since it is larger than the sum of its proper divisors (36570531).

81834561 is a wasteful number, since it uses less digits than its factorization.

81834561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15360 (or 15357 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 81834561 is about 9046.2456853658. The cubic root of 81834561 is about 434.1557784208.

The spelling of 81834561 in words is "eighty-one million, eight hundred thirty-four thousand, five hundred sixty-one".