521861369 has 2 divisors, whose sum is σ = 521861370. Its totient is φ = 521861368.

The previous prime is 521861341. The next prime is 521861377. The reversal of 521861369 is 963168125.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 475458025 + 46403344 = 21805^2 + 6812^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-521861369 is a prime.

It is a super-2 number, since 2×521861369² = 544678576909108322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (521861309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260930684 + 260930685.

It is an arithmetic number, because the mean of its divisors is an integer number (260930685).

Almost surely, 2^521861369 is an apocalyptic number.

It is an amenable number.

521861369 is a deficient number, since it is larger than the sum of its proper divisors (1).

521861369 is an equidigital number, since it uses as much as digits as its factorization.

521861369 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 41.

The square root of 521861369 is about 22844.2852591190. The cubic root of 521861369 is about 805.1035032739.

The spelling of 521861369 in words is "five hundred twenty-one million, eight hundred sixty-one thousand, three hundred sixty-nine".