209788732729 has 3 divisors (see below), whose sum is σ = 209789190757. Its totient is φ = 209788274702.

The previous prime is 209788732717. The next prime is 209788732799. The reversal of 209788732729 is 927237887902.

The square root of 209788732729 is 458027.

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.

It is not a de Polignac number, because 209788732729 - 2⁹ = 209788732217 is a prime.

It is a super-2 number, since 2×209788732729² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209788732799) 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, 229014 + ... + 687040.

Almost surely, 2^209788732729 is an apocalyptic number.

209788732729 is the 458027-th square number.

209788732729 is the 229014-th centered octagonal number.

It is an amenable number.

209788732729 is a deficient number, since it is larger than the sum of its proper divisors (458028).

209788732729 is an frugal number, since it uses more digits than its factorization.

209788732729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 916054 (or 458027 counting only the distinct ones).

The product of its (nonzero) digits is 42674688, while the sum is 64.

Multiplying 209788732729 by its sum of digits (64), we get a square (13426478894656 = 3664216²).

The spelling of 209788732729 in words is "two hundred nine billion, seven hundred eighty-eight million, seven hundred thirty-two thousand, seven hundred twenty-nine".