209749344256 has 51 divisors (see below), whose sum is σ = 419730105081. Its totient is φ = 104816050176.

The previous prime is 209749344157. The next prime is 209749344263. The reversal of 209749344256 is 652443947902.

The square root of 209749344256 is 457984.

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., 198188793856 + 11560550400 = 445184^2 + 107520^2 .

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 209749344197 and 209749344206.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 117243010 + ... + 117244798.

Almost surely, 2^209749344256 is an apocalyptic number.

209749344256 is the 457984-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209749344256

209749344256 is an abundant number, since it is smaller than the sum of its proper divisors (209980760825).

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

209749344256 is an frugal number, since it uses more digits than its factorization.

209749344256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3610 (or 1791 counting only the distinct ones).

The product of its (nonzero) digits is 13063680, while the sum is 55.

The spelling of 209749344256 in words is "two hundred nine billion, seven hundred forty-nine million, three hundred forty-four thousand, two hundred fifty-six".