209212015609 has 3 divisors (see below), whose sum is σ = 209212473007. Its totient is φ = 209211558212.

The previous prime is 209212015589. The next prime is 209212015643. The reversal of 209212015609 is 906510212902.

The square root of 209212015609 is 457397.

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., 67706642025 + 141505373584 = 260205^2 + 376172^2 .

It is not a de Polignac number, because 209212015609 - 2²⁹ = 208675144697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209212015709) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 228699 + ... + 686095.

Almost surely, 2^209212015609 is an apocalyptic number.

209212015609 is the 457397-th square number.

209212015609 is the 228699-th centered octagonal number.

It is an amenable number.

209212015609 is a deficient number, since it is larger than the sum of its proper divisors (457398).

209212015609 is an frugal number, since it uses more digits than its factorization.

209212015609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 914794 (or 457397 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 37.

The spelling of 209212015609 in words is "two hundred nine billion, two hundred twelve million, fifteen thousand, six hundred nine".