643091 has 4 divisors (see below), whose sum is σ = 646152. Its totient is φ = 640032.

The previous prime is 643087. The next prime is 643099. The reversal of 643091 is 190346.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 643091 - 2² = 643087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643099) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1190 + ... + 1643.

It is an arithmetic number, because the mean of its divisors is an integer number (161538).

2⁶⁴³⁰⁹¹ is an apocalyptic number.

643091 is a deficient number, since it is larger than the sum of its proper divisors (3061).

643091 is a wasteful number, since it uses less digits than its factorization.

643091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3060.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 643091 is about 801.9295480278. The cubic root of 643091 is about 86.3159014644.

The spelling of 643091 in words is "six hundred forty-three thousand, ninety-one".