643413521 has 2 divisors, whose sum is σ = 643413522. Its totient is φ = 643413520.

The previous prime is 643413497. The next prime is 643413539. The reversal of 643413521 is 125314346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 641912896 + 1500625 = 25336^2 + 1225^2 .

It is a cyclic number.

It is not a de Polignac number, because 643413521 - 2¹⁴ = 643397137 is a prime.

It is not a weakly prime, because it can be changed into another prime (643413541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321706760 + 321706761.

It is an arithmetic number, because the mean of its divisors is an integer number (321706761).

Almost surely, 2^643413521 is an apocalyptic number.

It is an amenable number.

643413521 is a deficient number, since it is larger than the sum of its proper divisors (1).

643413521 is an equidigital number, since it uses as much as digits as its factorization.

643413521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 29.

The square root of 643413521 is about 25365.5971938372. The cubic root of 643413521 is about 863.3032868037.

Adding to 643413521 its reverse (125314346), we get a palindrome (768727867).

The spelling of 643413521 in words is "six hundred forty-three million, four hundred thirteen thousand, five hundred twenty-one".