643415557 has 2 divisors, whose sum is σ = 643415558. Its totient is φ = 643415556.

The previous prime is 643415543. The next prime is 643415573. The reversal of 643415557 is 755514346.

643415557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 393585921 + 249829636 = 19839^2 + 15806^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643415557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643415537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321707778 + 321707779.

It is an arithmetic number, because the mean of its divisors is an integer number (321707779).

Almost surely, 2^643415557 is an apocalyptic number.

It is an amenable number.

643415557 is a deficient number, since it is larger than the sum of its proper divisors (1).

643415557 is an equidigital number, since it uses as much as digits as its factorization.

643415557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 252000, while the sum is 40.

The square root of 643415557 is about 25365.6373269035. The cubic root of 643415557 is about 863.3041974071.

The spelling of 643415557 in words is "six hundred forty-three million, four hundred fifteen thousand, five hundred fifty-seven".