643035521 has 2 divisors, whose sum is σ = 643035522. Its totient is φ = 643035520.

The previous prime is 643035457. The next prime is 643035527. The reversal of 643035521 is 125530346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 422097025 + 220938496 = 20545^2 + 14864^2 .

It is a cyclic number.

It is not a de Polignac number, because 643035521 - 2⁶ = 643035457 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 (643035527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321517760 + 321517761.

It is an arithmetic number, because the mean of its divisors is an integer number (321517761).

Almost surely, 2^643035521 is an apocalyptic number.

It is an amenable number.

643035521 is a deficient number, since it is larger than the sum of its proper divisors (1).

643035521 is an equidigital number, since it uses as much as digits as its factorization.

643035521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10800, while the sum is 29.

The square root of 643035521 is about 25358.1450622872. The cubic root of 643035521 is about 863.1341925598.

Adding to 643035521 its reverse (125530346), we get a palindrome (768565867).

The spelling of 643035521 in words is "six hundred forty-three million, thirty-five thousand, five hundred twenty-one".