643553165 has 16 divisors (see below), whose sum is σ = 777914496. Its totient is φ = 511089600.

The previous prime is 643553153. The next prime is 643553191. The reversal of 643553165 is 561355346.

It is not a de Polignac number, because 643553165 - 2⁶ = 643553101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 783455 + ... + 784275.

It is an arithmetic number, because the mean of its divisors is an integer number (48619656).

Almost surely, 2^643553165 is an apocalyptic number.

It is an amenable number.

643553165 is a deficient number, since it is larger than the sum of its proper divisors (134361331).

643553165 is a wasteful number, since it uses less digits than its factorization.

643553165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1780.

The product of its digits is 162000, while the sum is 38.

The square root of 643553165 is about 25368.3496704062. The cubic root of 643553165 is about 863.3657382959.

The spelling of 643553165 in words is "six hundred forty-three million, five hundred fifty-three thousand, one hundred sixty-five".