521541223261 has 2 divisors, whose sum is σ = 521541223262. Its totient is φ = 521541223260.

The previous prime is 521541223241. The next prime is 521541223367. The reversal of 521541223261 is 162322145125.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 323499312900 + 198041910361 = 568770^2 + 445019^2 .

It is a cyclic number.

It is not a de Polignac number, because 521541223261 - 2⁹ = 521541222749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521541223241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260770611630 + 260770611631.

It is an arithmetic number, because the mean of its divisors is an integer number (260770611631).

Almost surely, 2^521541223261 is an apocalyptic number.

It is an amenable number.

521541223261 is a deficient number, since it is larger than the sum of its proper divisors (1).

521541223261 is an equidigital number, since it uses as much as digits as its factorization.

521541223261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28800, while the sum is 34.

Adding to 521541223261 its reverse (162322145125), we get a palindrome (683863368386).

The spelling of 521541223261 in words is "five hundred twenty-one billion, five hundred forty-one million, two hundred twenty-three thousand, two hundred sixty-one".