643181 has 8 divisors (see below), whose sum is σ = 801984. Its totient is φ = 501120.

The previous prime is 643129. The next prime is 643183. The reversal of 643181 is 181346.

643181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643181 - 2¹⁰ = 642157 is a prime.

It is a super-2 number, since 2×643181² = 827363597522, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643181.

It is not an unprimeable number, because it can be changed into a prime (643183) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4100 + ... + 4253.

It is an arithmetic number, because the mean of its divisors is an integer number (100248).

2⁶⁴³¹⁸¹ is an apocalyptic number.

It is an amenable number.

643181 is a deficient number, since it is larger than the sum of its proper divisors (158803).

643181 is a wasteful number, since it uses less digits than its factorization.

643181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8371.

The product of its digits is 576, while the sum is 23.

The square root of 643181 is about 801.9856607197. The cubic root of 643181 is about 86.3199278871.

Adding to 643181 its sum of digits (23), we get a square (643204 = 802²).

The spelling of 643181 in words is "six hundred forty-three thousand, one hundred eighty-one".