231521513 has 2 divisors, whose sum is σ = 231521514. Its totient is φ = 231521512.

The previous prime is 231521501. The next prime is 231521531. The reversal of 231521513 is 315125132.

It is a happy number.

Together with next prime (231521531) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 217474009 + 14047504 = 14747^2 + 3748^2 .

It is a cyclic number.

It is not a de Polignac number, because 231521513 - 2⁴ = 231521497 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (231521813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115760756 + 115760757.

It is an arithmetic number, because the mean of its divisors is an integer number (115760757).

Almost surely, 2^231521513 is an apocalyptic number.

It is an amenable number.

231521513 is a deficient number, since it is larger than the sum of its proper divisors (1).

231521513 is an equidigital number, since it uses as much as digits as its factorization.

231521513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 900, while the sum is 23.

The square root of 231521513 is about 15215.8309993244. The cubic root of 231521513 is about 614.0406423033.

Adding to 231521513 its reverse (315125132), we get a palindrome (546646645).

The spelling of 231521513 in words is "two hundred thirty-one million, five hundred twenty-one thousand, five hundred thirteen".