643577121 has 12 divisors (see below), whose sum is σ = 1014121680. Its totient is φ = 390046680.

The previous prime is 643577119. The next prime is 643577131. The reversal of 643577121 is 121775346.

It is a happy number.

643577121 is a `hidden beast` number, since 64 + 3 + 577 + 1 + 21 = 666.

It is not a de Polignac number, because 643577121 - 2¹ = 643577119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643577111) 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 in 11 ways as a sum of consecutive naturals, for example, 3250291 + ... + 3250488.

It is an arithmetic number, because the mean of its divisors is an integer number (84510140).

Almost surely, 2^643577121 is an apocalyptic number.

It is an amenable number.

643577121 is a deficient number, since it is larger than the sum of its proper divisors (370544559).

643577121 is a wasteful number, since it uses less digits than its factorization.

643577121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6500796 (or 6500793 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 643577121 is about 25368.8218291666. The cubic root of 643577121 is about 863.3764509737.

The spelling of 643577121 in words is "six hundred forty-three million, five hundred seventy-seven thousand, one hundred twenty-one".