521893721 has 2 divisors, whose sum is σ = 521893722. Its totient is φ = 521893720.

The previous prime is 521893663. The next prime is 521893733. The reversal of 521893721 is 127398125.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 485761600 + 36132121 = 22040^2 + 6011^2 .

It is a cyclic number.

It is not a de Polignac number, because 521893721 - 2¹⁰ = 521892697 is a prime.

It is not a weakly prime, because it can be changed into another prime (521893741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260946860 + 260946861.

It is an arithmetic number, because the mean of its divisors is an integer number (260946861).

Almost surely, 2^521893721 is an apocalyptic number.

It is an amenable number.

521893721 is a deficient number, since it is larger than the sum of its proper divisors (1).

521893721 is an equidigital number, since it uses as much as digits as its factorization.

521893721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 38.

The square root of 521893721 is about 22844.9933464643. The cubic root of 521893721 is about 805.1201399849.

The spelling of 521893721 in words is "five hundred twenty-one million, eight hundred ninety-three thousand, seven hundred twenty-one".