243521 has 2 divisors, whose sum is σ = 243522. Its totient is φ = 243520.

The previous prime is 243517. The next prime is 243527. The reversal of 243521 is 125342.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 160000 + 83521 = 400^2 + 289^2 .

It is a cyclic number.

It is not a de Polignac number, because 243521 - 2² = 243517 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 243521.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 243521.

It is not a weakly prime, because it can be changed into another prime (243527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121760 + 121761.

It is an arithmetic number, because the mean of its divisors is an integer number (121761).

2²⁴³⁵²¹ is an apocalyptic number.

It is an amenable number.

243521 is a deficient number, since it is larger than the sum of its proper divisors (1).

243521 is an equidigital number, since it uses as much as digits as its factorization.

243521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 240, while the sum is 17.

The square root of 243521 is about 493.4784696418. The cubic root of 243521 is about 62.4470805385.

Adding to 243521 its reverse (125342), we get a palindrome (368863).

The spelling of 243521 in words is "two hundred forty-three thousand, five hundred twenty-one".