209647684129 has 9 divisors (see below), whose sum is σ = 227021393529. Its totient is φ = 193515444720.

The previous prime is 209647684111. The next prime is 209647684153. The reversal of 209647684129 is 921486746902.

The square root of 209647684129 is 457873.

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 3393645025 + 206254039104 = 58255^2 + 454152^2 .

It is not a de Polignac number, because 209647684129 - 2⁵ = 209647684097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209647684229) 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, 5934739 + ... + 5969959.

It is an arithmetic number, because the mean of its divisors is an integer number (25224599281).

Almost surely, 2^209647684129 is an apocalyptic number.

209647684129 is the 457873-rd square number.

209647684129 is the 228937-th centered octagonal number.

It is an amenable number.

209647684129 is a deficient number, since it is larger than the sum of its proper divisors (17373709400).

209647684129 is an frugal number, since it uses more digits than its factorization.

209647684129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70468 (or 35234 counting only the distinct ones).

The product of its (nonzero) digits is 10450944, while the sum is 58.

The spelling of 209647684129 in words is "two hundred nine billion, six hundred forty-seven million, six hundred eighty-four thousand, one hundred twenty-nine".