421209 has 12 divisors (see below), whose sum is σ = 644436. Its totient is φ = 264192.

The previous prime is 421207. The next prime is 421241. The reversal of 421209 is 902124.

It can be written as a sum of positive squares in 2 ways, for example, as 363609 + 57600 = 603^2 + 240^2 .

It is not a de Polignac number, because 421209 - 2¹ = 421207 is a prime.

It is an Ulam number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 421191 and 421200.

It is not an unprimeable number, because it can be changed into a prime (421207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1224 + ... + 1529.

It is an arithmetic number, because the mean of its divisors is an integer number (53703).

2⁴²¹²⁰⁹ is an apocalyptic number.

It is an amenable number.

421209 is a deficient number, since it is larger than the sum of its proper divisors (223227).

421209 is a wasteful number, since it uses less digits than its factorization.

421209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2776 (or 2773 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 421209 is about 649.0061632989. The cubic root of 421209 is about 74.9605125469.

It can be divided in two parts, 421 and 209, that added together give a triangular number (630 = T₃₅).

The spelling of 421209 in words is "four hundred twenty-one thousand, two hundred nine".