231521 has 4 divisors (see below), whose sum is σ = 233472. Its totient is φ = 229572.

The previous prime is 231503. The next prime is 231529. The reversal of 231521 is 125132.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231521 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 231496 and 231505.

It is not an unprimeable number, because it can be changed into a prime (231529) 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, 785 + ... + 1038.

It is an arithmetic number, because the mean of its divisors is an integer number (58368).

2²³¹⁵²¹ is an apocalyptic number.

It is an amenable number.

231521 is a deficient number, since it is larger than the sum of its proper divisors (1951).

231521 is a wasteful number, since it uses less digits than its factorization.

231521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1950.

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

The square root of 231521 is about 481.1662914212. The cubic root of 231521 is about 61.4040188777.

Adding to 231521 its reverse (125132), we get a palindrome (356653).

The spelling of 231521 in words is "two hundred thirty-one thousand, five hundred twenty-one".