81225 has 27 divisors (see below), whose sum is σ = 153543. Its totient is φ = 41040.

The previous prime is 81223. The next prime is 81233. The reversal of 81225 is 52218.

81225 = T_{284} + T_{285}.

The square root of 81225 is 285.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 29241 + 51984 = 171^2 + 228^2 .

It is not a de Polignac number, because 81225 - 2^{1} = 81223 is a prime.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a junction number, because it is equal to *n*+sod(*n*) for *n* = 81198 and 81207.

It is not an unprimeable number, because it can be changed into a prime (81223) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 4266 + ... + 4284.

81225 is a Friedman number, since it can be written as 285^2*1, using all its digits and the basic arithmetic operations.

2^{81225} is an apocalyptic number.

81225 is the 285-th square number.

81225 is the 143-rd centered octagonal number.

It is an amenable number.

81225 is a deficient number, since it is larger than the sum of its proper divisors (72318).

81225 is a wasteful number, since it uses less digits than its factorization.

81225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54 (or 27 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The cubic root of 81225 is about 43.3075125595.

It can be divided in two parts, 81 and 225, that multiplied together give a square (18225 = 135^{2}).

The spelling of 81225 in words is "eighty-one thousand, two hundred twenty-five".

Divisors: 1 3 5 9 15 19 25 45 57 75 95 171 225 285 361 475 855 1083 1425 1805 3249 4275 5415 9025 16245 27075 81225

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