643621057 has 2 divisors, whose sum is σ = 643621058. Its totient is φ = 643621056.

The previous prime is 643621019. The next prime is 643621061. The reversal of 643621057 is 750126346.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 559275201 + 84345856 = 23649^2 + 9184^2 .

It is a cyclic number.

It is not a de Polignac number, because 643621057 - 2²⁷ = 509403329 is a prime.

It is not a weakly prime, because it can be changed into another prime (643621007) 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, 321810528 + 321810529.

It is an arithmetic number, because the mean of its divisors is an integer number (321810529).

Almost surely, 2^643621057 is an apocalyptic number.

It is an amenable number.

643621057 is a deficient number, since it is larger than the sum of its proper divisors (1).

643621057 is an equidigital number, since it uses as much as digits as its factorization.

643621057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 34.

The square root of 643621057 is about 25369.6877592138. The cubic root of 643621057 is about 863.3960976450.

The spelling of 643621057 in words is "six hundred forty-three million, six hundred twenty-one thousand, fifty-seven".