209563443961 has 9 divisors (see below), whose sum is σ = 213203046981. Its totient is φ = 205984969884.

The previous prime is 209563443959. The next prime is 209563443989. The reversal of 209563443961 is 169344365902.

The square root of 209563443961 is 457781.

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

It is not a de Polignac number, because 209563443961 - 2¹ = 209563443959 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 209563443899 and 209563443908.

It is not an unprimeable number, because it can be changed into a prime (209563443941) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 27005200 + ... + 27012958.

Almost surely, 2^209563443961 is an apocalyptic number.

209563443961 is the 457781-st square number.

209563443961 is the 228891-st centered octagonal number.

It is an amenable number.

209563443961 is a deficient number, since it is larger than the sum of its proper divisors (3639603020).

209563443961 is an frugal number, since it uses more digits than its factorization.

209563443961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15636 (or 7818 counting only the distinct ones).

The product of its (nonzero) digits is 4199040, while the sum is 52.

The spelling of 209563443961 in words is "two hundred nine billion, five hundred sixty-three million, four hundred forty-three thousand, nine hundred sixty-one".