209706389856 has 240 divisors, whose sum is σ = 633148084800. Its totient is φ = 68066998272.

The previous prime is 209706389833. The next prime is 209706389857. The reversal of 209706389856 is 658983607902.

It is a junction number, because it is equal to n+sod(n) for n = 209706389793 and 209706389802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209706389857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 14941050 + ... + 14955078.

It is an arithmetic number, because the mean of its divisors is an integer number (2638117020).

Almost surely, 2^209706389856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209706389856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (316574042400).

209706389856 is an abundant number, since it is smaller than the sum of its proper divisors (423441694944).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

209706389856 is a wasteful number, since it uses less digits than its factorization.

209706389856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14203 (or 14186 counting only the distinct ones).

The product of its (nonzero) digits is 39191040, while the sum is 63.

The spelling of 209706389856 in words is "two hundred nine billion, seven hundred six million, three hundred eighty-nine thousand, eight hundred fifty-six".