521581 has 2 divisors, whose sum is σ = 521582. Its totient is φ = 521580.

The previous prime is 521567. The next prime is 521603. The reversal of 521581 is 185125.

It is an a-pointer prime, because the next prime (521603) can be obtained adding 521581 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 477481 + 44100 = 691^2 + 210^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-521581 is a prime.

It is a super-2 number, since 2×521581² = 544093479122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260790 + 260791.

It is an arithmetic number, because the mean of its divisors is an integer number (260791).

2⁵²¹⁵⁸¹ is an apocalyptic number.

It is an amenable number.

521581 is a deficient number, since it is larger than the sum of its proper divisors (1).

521581 is an equidigital number, since it uses as much as digits as its factorization.

521581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 400, while the sum is 22.

The square root of 521581 is about 722.2056493825. The cubic root of 521581 is about 80.4959297352.

The spelling of 521581 in words is "five hundred twenty-one thousand, five hundred eighty-one".