641209 has 4 divisors (see below), whose sum is σ = 642816. Its totient is φ = 639604.

The previous prime is 641203. The next prime is 641213. The reversal of 641209 is 902146.

641209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 641209 - 2¹⁷ = 510137 is a prime.

It is a super-2 number, since 2×641209² = 822297963362, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 641209.

It is not an unprimeable number, because it can be changed into a prime (641203) 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, 312 + ... + 1174.

It is an arithmetic number, because the mean of its divisors is an integer number (160704).

2⁶⁴¹²⁰⁹ is an apocalyptic number.

It is an amenable number.

641209 is a deficient number, since it is larger than the sum of its proper divisors (1607).

641209 is an equidigital number, since it uses as much as digits as its factorization.

641209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1606.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 641209 is about 800.7552684810. The cubic root of 641209 is about 86.2316182910.

The spelling of 641209 in words is "six hundred forty-one thousand, two hundred nine".