1225 has 9 divisors (see below), whose sum is σ = 1767. Its totient is φ = 840.

The previous prime is 1223. The next prime is 1229. The reversal of 1225 is 5221.

1225 = T₃₄ + T₃₅.

The square root of 1225 is 35.

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

1225 is a nontrivial binomial coefficient, being equal to C(50, 2).

It can be written as a sum of positive squares in only one way, i.e., 441 + 784 = 21^2 + 28^2 .

It is not a de Polignac number, because 1225 - 2¹ = 1223 is a prime.

It is a Duffinian number.

It is a plaindrome in base 10 and base 15.

It is a nialpdrome in base 12 and base 13.

It is not an unprimeable number, because it can be changed into a prime (1223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 172 + ... + 178.

1225 is the 49-th triangular number, the 35-th square number and also the 25-th hexagonal number.

1225 is the 18-th centered octagonal number and also the 17-th centered nonagonal number.

It is an amenable number.

1225 is a deficient number, since it is larger than the sum of its proper divisors (542).

1225 is an equidigital number, since it uses as much as digits as its factorization.

1225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24 (or 12 counting only the distinct ones).

The product of its digits is 20, while the sum is 10.

The cubic root of 1225 is about 10.6998748057.

Adding to 1225 its reverse (5221), we get a palindrome (6446).

It can be divided in two parts, 12 and 25, that multiplied together give a triangular number (300 = T₂₄).

The spelling of 1225 in words is "one thousand, two hundred twenty-five".