521861 has 2 divisors, whose sum is σ = 521862. Its totient is φ = 521860.

The previous prime is 521831. The next prime is 521869. The reversal of 521861 is 168125.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 516961 + 4900 = 719^2 + 70^2 .

It is a cyclic number.

It is not a de Polignac number, because 521861 - 2¹⁰ = 520837 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260930 + 260931.

It is an arithmetic number, because the mean of its divisors is an integer number (260931).

2⁵²¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

521861 is a deficient number, since it is larger than the sum of its proper divisors (1).

521861 is an equidigital number, since it uses as much as digits as its factorization.

521861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 480, while the sum is 23.

The square root of 521861 is about 722.3994739754. The cubic root of 521861 is about 80.5103313515.

Adding to 521861 its reverse (168125), we get a palindrome (689986).

The spelling of 521861 in words is "five hundred twenty-one thousand, eight hundred sixty-one".