123521 has 4 divisors (see below), whose sum is σ = 124500. Its totient is φ = 122544.

The previous prime is 123517. The next prime is 123527. The reversal of 123521 is 125321.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 125321 = 7 ⋅17903.

It can be written as a sum of positive squares in 2 ways, for example, as 40000 + 83521 = 200^2 + 289^2 .

It is a cyclic number.

It is not a de Polignac number, because 123521 - 2² = 123517 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 123496 and 123505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123527) 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 3 ways as a sum of consecutive naturals, for example, 266 + ... + 563.

It is an arithmetic number, because the mean of its divisors is an integer number (31125).

2¹²³⁵²¹ is an apocalyptic number.

It is an amenable number.

123521 is a deficient number, since it is larger than the sum of its proper divisors (979).

123521 is an equidigital number, since it uses as much as digits as its factorization.

123521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 978.

The product of its digits is 60, while the sum is 14.

The square root of 123521 is about 351.4555448417. The cubic root of 123521 is about 49.8020170901.

Adding to 123521 its reverse (125321), we get a palindrome (248842).

The spelling of 123521 in words is "one hundred twenty-three thousand, five hundred twenty-one".