201231521 has 4 divisors (see below), whose sum is σ = 201918612. Its totient is φ = 200544432.

The previous prime is 201231517. The next prime is 201231553. The reversal of 201231521 is 125132102.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125132102 = 2 ⋅62566051.

It can be written as a sum of positive squares in 2 ways, for example, as 102010000 + 99221521 = 10100^2 + 9961^2 .

It is a cyclic number.

It is not a de Polignac number, because 201231521 - 2² = 201231517 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 201231521.

It is not an unprimeable number, because it can be changed into a prime (201231221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 343106 + ... + 343691.

It is an arithmetic number, because the mean of its divisors is an integer number (50479653).

Almost surely, 2^201231521 is an apocalyptic number.

It is an amenable number.

201231521 is a deficient number, since it is larger than the sum of its proper divisors (687091).

201231521 is an equidigital number, since it uses as much as digits as its factorization.

201231521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 687090.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 201231521 is about 14185.6096449888. The cubic root of 201231521 is about 586.0014220671.

Adding to 201231521 its reverse (125132102), we get a palindrome (326363623).

It can be divided in two parts, 2012 and 31521, that added together give a palindrome (33533).

The spelling of 201231521 in words is "two hundred one million, two hundred thirty-one thousand, five hundred twenty-one".