1231544521 has 2 divisors, whose sum is σ = 1231544522. Its totient is φ = 1231544520.

The previous prime is 1231544513. The next prime is 1231544551. The reversal of 1231544521 is 1254451321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 878292496 + 353252025 = 29636^2 + 18795^2 .

It is an emirp because it is prime and its reverse (1254451321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1231544521 - 2³ = 1231544513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1231544521.

It is not a weakly prime, because it can be changed into another prime (1231544551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615772260 + 615772261.

It is an arithmetic number, because the mean of its divisors is an integer number (615772261).

Almost surely, 2^1231544521 is an apocalyptic number.

It is an amenable number.

1231544521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231544521 is an equidigital number, since it uses as much as digits as its factorization.

1231544521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4800, while the sum is 28.

The square root of 1231544521 is about 35093.3686185866. The cubic root of 1231544521 is about 1071.8895546092.

Adding to 1231544521 its reverse (1254451321), we get a palindrome (2485995842).

The spelling of 1231544521 in words is "one billion, two hundred thirty-one million, five hundred forty-four thousand, five hundred twenty-one".