521522721 has 12 divisors (see below), whose sum is σ = 757474900. Its totient is φ = 345759840.

The previous prime is 521522711. The next prime is 521522767. The reversal of 521522721 is 127225125.

It can be written as a sum of positive squares in 2 ways, for example, as 17969121 + 503553600 = 4239^2 + 22440^2 .

It is not a de Polignac number, because 521522721 - 2¹⁵ = 521489953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521522711) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 158446 + ... + 161703.

Almost surely, 2^521522721 is an apocalyptic number.

It is an amenable number.

521522721 is a deficient number, since it is larger than the sum of its proper divisors (235952179).

521522721 is a wasteful number, since it uses less digits than its factorization.

521522721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320336 (or 320333 counting only the distinct ones).

The product of its digits is 2800, while the sum is 27.

The square root of 521522721 is about 22836.8719618077. The cubic root of 521522721 is about 804.9293154504.

Adding to 521522721 its reverse (127225125), we get a palindrome (648747846).

The spelling of 521522721 in words is "five hundred twenty-one million, five hundred twenty-two thousand, seven hundred twenty-one".