521299981 has 2 divisors, whose sum is σ = 521299982. Its totient is φ = 521299980.

The previous prime is 521299939. The next prime is 521300057. The reversal of 521299981 is 189992125.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 509224356 + 12075625 = 22566^2 + 3475^2 .

It is a cyclic number.

It is not a de Polignac number, because 521299981 - 2⁹ = 521299469 is a prime.

It is a super-2 number, since 2×521299981² = 543507340381200722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521299921) 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, 260649990 + 260649991.

It is an arithmetic number, because the mean of its divisors is an integer number (260649991).

Almost surely, 2^521299981 is an apocalyptic number.

It is an amenable number.

521299981 is a deficient number, since it is larger than the sum of its proper divisors (1).

521299981 is an equidigital number, since it uses as much as digits as its factorization.

521299981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 46.

The square root of 521299981 is about 22831.9946785208. The cubic root of 521299981 is about 804.8147052400.

The spelling of 521299981 in words is "five hundred twenty-one million, two hundred ninety-nine thousand, nine hundred eighty-one".