209867520769 has 9 divisors (see below), whose sum is σ = 217367637097. Its totient is φ = 202617882544.

The previous prime is 209867520767. The next prime is 209867520773. The reversal of 209867520769 is 967025768902.

The square root of 209867520769 is 458113.

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

It can be written as a sum of positive squares in 4 ways, for example, as 14071890625 + 195795630144 = 118625^2 + 442488^2 .

It is not a de Polignac number, because 209867520769 - 2¹ = 209867520767 is a prime.

It is a super-3 number, since 3×209867520769³ (a number of 35 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209867520767) 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, 13277379 + ... + 13293175.

Almost surely, 2^209867520769 is an apocalyptic number.

209867520769 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

209867520769 is the 458113-rd square number.

209867520769 is the 229057-th centered octagonal number.

It is an amenable number.

209867520769 is a deficient number, since it is larger than the sum of its proper divisors (7500116328).

209867520769 is an frugal number, since it uses more digits than its factorization.

209867520769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31652 (or 15826 counting only the distinct ones).

The product of its (nonzero) digits is 22861440, while the sum is 61.

The spelling of 209867520769 in words is "two hundred nine billion, eight hundred sixty-seven million, five hundred twenty thousand, seven hundred sixty-nine".