521393993 has 2 divisors, whose sum is σ = 521393994. Its totient is φ = 521393992.

The previous prime is 521393989. The next prime is 521394001. The reversal of 521393993 is 399393125.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 374693449 + 146700544 = 19357^2 + 12112^2 .

It is a cyclic number.

It is not a de Polignac number, because 521393993 - 2² = 521393989 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (521393903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260696996 + 260696997.

It is an arithmetic number, because the mean of its divisors is an integer number (260696997).

Almost surely, 2^521393993 is an apocalyptic number.

It is an amenable number.

521393993 is a deficient number, since it is larger than the sum of its proper divisors (1).

521393993 is an equidigital number, since it uses as much as digits as its factorization.

521393993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 196830, while the sum is 44.

The square root of 521393993 is about 22834.0533633431. The cubic root of 521393993 is about 804.8630828184.

The spelling of 521393993 in words is "five hundred twenty-one million, three hundred ninety-three thousand, nine hundred ninety-three".