209931121 has 3 divisors (see below), whose sum is σ = 209945611. Its totient is φ = 209916632.

The previous prime is 209931091. The next prime is 209931131. The reversal of 209931121 is 121139902.

The square root of 209931121 is 14489.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 30371121 + 179560000 = 5511^2 + 13400^2 .

It is not a de Polignac number, because 209931121 - 2⁵ = 209931089 is a prime.

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 209931121.

It is not an unprimeable number, because it can be changed into a prime (209931131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 7245 + ... + 21733.

Almost surely, 2^209931121 is an apocalyptic number.

209931121 is the 14489-th square number.

209931121 is the 7245-th centered octagonal number.

It is an amenable number.

209931121 is a deficient number, since it is larger than the sum of its proper divisors (14490).

209931121 is an frugal number, since it uses more digits than its factorization.

209931121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28978 (or 14489 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 28.

The cubic root of 209931121 is about 594.3272022335.

The spelling of 209931121 in words is "two hundred nine million, nine hundred thirty-one thousand, one hundred twenty-one".