• 225 can be written using four 4's:

225 has 9 divisors (see below), whose sum is σ = 403. Its totient is φ = 120.

The previous prime is 223. The next prime is 227. The reversal of 225 is 522.

225 = T_{14} + T_{15}.

225 = 1^{3} + 2^{3} + ... + 5^{3}.

The square root of 225 is 15.

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

225 is nontrivially palindromic in base 14.

225 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

225 is an esthetic number in base 14, because in such base its adjacent digits differ by 1.

It is an interprime number because it is at equal distance from previous prime (223) and next prime (227).

It can be written as a sum of positive squares in only one way, i.e., 81 + 144 = 9^2 + 12^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 225 - 2^{1} = 223 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

225 is an undulating number in base 14.

225 is strictly pandigital in base 4.

It is a plaindrome in base 10, base 12 and base 13.

It is a nialpdrome in base 3, base 7, base 15 and base 16.

It is not an unprimeable number, because it can be changed into a prime (223) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 43 + ... + 47.

It is a Proth number, since it is equal to 7 ⋅ 2^{5} + 1 and 7 < 2^{5}.

225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

225 is the 15-th square number and also the 9-th octagonal number.

225 is the 8-th centered octagonal number.

It is an amenable number.

225 is a deficient number, since it is larger than the sum of its proper divisors (178).

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

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

The sum of its prime factors is 16 (or 8 counting only the distinct ones).

The product of its digits is 20, while the sum is 9.

The cubic root of 225 is about 6.0822019956.

Adding to 225 its reverse (522), we get a palindrome (747).

It can be divided in two parts, 22 and 5, that added together give a cube (27 = 3^{3}).

The spelling of 225 in words is "two hundred twenty-five", and thus it is an aban number.

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