209123965728 has 768 divisors, whose sum is σ = 705438720000. Its totient is φ = 59907133440.

The previous prime is 209123965693. The next prime is 209123965819. The reversal of 209123965728 is 827569321902.

209123965728 is a `hidden beast` number, since 20 + 9 + 12 + 39 + 6 + 572 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 777412378 + ... + 777412646.

It is an arithmetic number, because the mean of its divisors is an integer number (918540000).

Almost surely, 2^209123965728 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 209123965728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (352719360000).

209123965728 is an abundant number, since it is smaller than the sum of its proper divisors (496314754272).

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

209123965728 is a wasteful number, since it uses less digits than its factorization.

209123965728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 430 (or 416 counting only the distinct ones).

The product of its (nonzero) digits is 3265920, while the sum is 54.

The spelling of 209123965728 in words is "two hundred nine billion, one hundred twenty-three million, nine hundred sixty-five thousand, seven hundred twenty-eight".