209421 has 6 divisors (see below), whose sum is σ = 302510. Its totient is φ = 139608.

The previous prime is 209401. The next prime is 209431. The reversal of 209421 is 124902.

It can be written as a sum of positive squares in only one way, i.e., 171396 + 38025 = 414^2 + 195^2 .

It is not a de Polignac number, because 209421 - 2⁶ = 209357 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

209421 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 209394 and 209403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209401) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11626 + ... + 11643.

2²⁰⁹⁴²¹ is an apocalyptic number.

It is an amenable number.

209421 is a deficient number, since it is larger than the sum of its proper divisors (93089).

209421 is a wasteful number, since it uses less digits than its factorization.

209421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23275 (or 23272 counting only the distinct ones).

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

The square root of 209421 is about 457.6253926521. The cubic root of 209421 is about 59.3845417722.

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

The spelling of 209421 in words is "two hundred nine thousand, four hundred twenty-one".