521323021 has 2 divisors, whose sum is σ = 521323022. Its totient is φ = 521323020.

The previous prime is 521323009. The next prime is 521323027. The reversal of 521323021 is 120323125.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 435556900 + 85766121 = 20870^2 + 9261^2 .

It is a cyclic number.

It is not a de Polignac number, because 521323021 - 2²¹ = 519225869 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 521323021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521323027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260661510 + 260661511.

It is an arithmetic number, because the mean of its divisors is an integer number (260661511).

Almost surely, 2^521323021 is an apocalyptic number.

It is an amenable number.

521323021 is a deficient number, since it is larger than the sum of its proper divisors (1).

521323021 is an equidigital number, since it uses as much as digits as its factorization.

521323021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 521323021 is about 22832.4992280740. The cubic root of 521323021 is about 804.8265619177.

Adding to 521323021 its reverse (120323125), we get a palindrome (641646146).

The spelling of 521323021 in words is "five hundred twenty-one million, three hundred twenty-three thousand, twenty-one".