643266161 has 4 divisors (see below), whose sum is σ = 643597824. Its totient is φ = 642934500.

The previous prime is 643266157. The next prime is 643266229. The reversal of 643266161 is 161662346.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 643266161 - 2² = 643266157 is a prime.

It is a super-5 number, since 5×643266161⁵ (a number of 45 digits) contains 55555 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (643266121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 162905 + ... + 166806.

It is an arithmetic number, because the mean of its divisors is an integer number (160899456).

Almost surely, 2^643266161 is an apocalyptic number.

It is an amenable number.

643266161 is a deficient number, since it is larger than the sum of its proper divisors (331663).

643266161 is a wasteful number, since it uses less digits than its factorization.

643266161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331662.

The product of its digits is 31104, while the sum is 35.

The square root of 643266161 is about 25362.6923058259. The cubic root of 643266161 is about 863.2373747676.

The spelling of 643266161 in words is "six hundred forty-three million, two hundred sixty-six thousand, one hundred sixty-one".