521421521 has 6 divisors (see below), whose sum is σ = 527786370. Its totient is φ = 515132528.

The previous prime is 521421517. The next prime is 521421529. The reversal of 521421521 is 125124125.

It can be written as a sum of positive squares in only one way, i.e., 520980625 + 440896 = 22825^2 + 664^2 .

It is not a de Polignac number, because 521421521 - 2² = 521421517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521421529) 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 in 5 ways as a sum of consecutive naturals, for example, 30956 + ... + 44733.

It is an arithmetic number, because the mean of its divisors is an integer number (87964395).

Almost surely, 2^521421521 is an apocalyptic number.

It is an amenable number.

521421521 is a deficient number, since it is larger than the sum of its proper divisors (6364849).

521421521 is an frugal number, since it uses more digits than its factorization.

521421521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75855 (or 75772 counting only the distinct ones).

The product of its digits is 800, while the sum is 23.

The square root of 521421521 is about 22834.6561392984. The cubic root of 521421521 is about 804.8772473346.

Adding to 521421521 its reverse (125124125), we get a palindrome (646545646).

The spelling of 521421521 in words is "five hundred twenty-one million, four hundred twenty-one thousand, five hundred twenty-one".