231978521 has 2 divisors, whose sum is σ = 231978522. Its totient is φ = 231978520.

The previous prime is 231978497. The next prime is 231978553. The reversal of 231978521 is 125879132.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 229219600 + 2758921 = 15140^2 + 1661^2 .

It is a cyclic number.

It is not a de Polignac number, because 231978521 - 2¹⁰ = 231977497 is a prime.

It is not a weakly prime, because it can be changed into another prime (231918521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115989260 + 115989261.

It is an arithmetic number, because the mean of its divisors is an integer number (115989261).

Almost surely, 2^231978521 is an apocalyptic number.

It is an amenable number.

231978521 is a deficient number, since it is larger than the sum of its proper divisors (1).

231978521 is an equidigital number, since it uses as much as digits as its factorization.

231978521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 38.

The square root of 231978521 is about 15230.8411126897. The cubic root of 231978521 is about 614.4444018240. Note that the first 4 decimals are identical.

The spelling of 231978521 in words is "two hundred thirty-one million, nine hundred seventy-eight thousand, five hundred twenty-one".