1521 has 9 divisors (see below), whose sum is σ = 2379. Its totient is φ = 936.

The previous prime is 1511. The next prime is 1523. The reversal of 1521 is 1251.

1521 = T_{38} + T_{39}.

It is a happy number.

The square root of 1521 is 39.

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

1521 is nontrivially palindromic in base 15.

It can be written as a sum of positive squares in only one way, i.e., 225 + 1296 = 15^2 + 36^2 .

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

It is not a de Polignac number, because 1521 - 2^{5} = 1489 is a prime.

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

1521 is an undulating number in base 15.

It is a nialpdrome in base 13.

It is an inconsummate number, since it does not exist a number *n* which divided by its sum of digits gives 1521.

It is not an unprimeable number, because it can be changed into a prime (1523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 111 + ... + 123.

1521 is the 39-th square number.

1521 is the 20-th centered octagonal number.

It is an amenable number.

1521 is a deficient number, since it is larger than the sum of its proper divisors (858).

1521 is a wasteful number, since it uses less digits than its factorization.

With its predecessor (1520) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (32).

1521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32 (or 16 counting only the distinct ones).

The product of its digits is 10, while the sum is 9.

The cubic root of 1521 is about 11.5003150512.

Adding to 1521 its reverse (1251), we get a palindrome (2772).

It can be divided in two parts, 152 and 1, that added together give a triangular number (153 = T_{17}).

The spelling of 1521 in words is "one thousand, five hundred twenty-one".

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