643556606501 has 2 divisors, whose sum is σ = 643556606502. Its totient is φ = 643556606500.

The previous prime is 643556606471. The next prime is 643556606513. The reversal of 643556606501 is 105606655346.

643556606501 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 635671344100 + 7885262401 = 797290^2 + 88799^2 .

It is a cyclic number.

It is not a de Polignac number, because 643556606501 - 2¹⁸ = 643556344357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643556606521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321778303250 + 321778303251.

It is an arithmetic number, because the mean of its divisors is an integer number (321778303251).

Almost surely, 2^643556606501 is an apocalyptic number.

It is an amenable number.

643556606501 is a deficient number, since it is larger than the sum of its proper divisors (1).

643556606501 is an equidigital number, since it uses as much as digits as its factorization.

643556606501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944000, while the sum is 47.

The spelling of 643556606501 in words is "six hundred forty-three billion, five hundred fifty-six million, six hundred six thousand, five hundred one".