209966562589729 has 81 divisors (see below), whose sum is σ = 238516955142739. Its totient is φ = 184693541575840.

The previous prime is 209966562589681. The next prime is 209966562589739. The reversal of 209966562589729 is 927985265669902.

The square root of 209966562589729 is 14490223.

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

It can be written as a sum of positive squares in only one way, i.e., 13814773213329 + 196151789376400 = 3716823^2 + 14005420^2 .

It is not a de Polignac number, because 209966562589729 - 2¹⁷ = 209966562458657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209966562589739) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 780544842207 + ... + 780544842475.

Almost surely, 2^{209966562589729} is an apocalyptic number.

209966562589729 is the 14490223-rd square number.

209966562589729 is the 7245112-nd centered octagonal number.

It is an amenable number.

209966562589729 is a deficient number, since it is larger than the sum of its proper divisors (28550392553010).

209966562589729 is an frugal number, since it uses more digits than its factorization.

209966562589729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 844 (or 422 counting only the distinct ones).

The product of its (nonzero) digits is 15872371200, while the sum is 85.

The spelling of 209966562589729 in words is "two hundred nine trillion, nine hundred sixty-six billion, five hundred sixty-two million, five hundred eighty-nine thousand, seven hundred twenty-nine".