209277885961 has 3 divisors (see below), whose sum is σ = 209278343431. Its totient is φ = 209277428492.

The previous prime is 209277885959. The next prime is 209277885991. The reversal of 209277885961 is 169588772902.

The square root of 209277885961 is 457469.

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, and also an emirpimes, since its reverse is a distinct semiprime: 169588772902 = 2 ⋅84794386451.

It can be written as a sum of positive squares in only one way, i.e., 150180275961 + 59097610000 = 387531^2 + 243100^2 .

It is not a de Polignac number, because 209277885961 - 2¹ = 209277885959 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 209277885893 and 209277885902.

It is not an unprimeable number, because it can be changed into a prime (209277885911) 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, 228735 + ... + 686203.

Almost surely, 2^209277885961 is an apocalyptic number.

209277885961 is the 457469-th square number.

209277885961 is the 228735-th centered octagonal number.

It is an amenable number.

209277885961 is a deficient number, since it is larger than the sum of its proper divisors (457470).

209277885961 is an frugal number, since it uses more digits than its factorization.

209277885961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 914938 (or 457469 counting only the distinct ones).

The product of its (nonzero) digits is 30481920, while the sum is 64.

Multiplying 209277885961 by its sum of digits (64), we get a square (13393784701504 = 3659752²).

The spelling of 209277885961 in words is "two hundred nine billion, two hundred seventy-seven million, eight hundred eighty-five thousand, nine hundred sixty-one".