209728780800 has 720 divisors, whose sum is σ = 879294426912. Its totient is φ = 43575705600.

The previous prime is 209728780733. The next prime is 209728780913. The reversal of 209728780800 is 8087827902.

It is a happy number.

It is a super-2 number, since 2×209728780800² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 20692534 + ... + 20702666.

Almost surely, 2^209728780800 is an apocalyptic number.

209728780800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209728780800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (439647213456).

209728780800 is an abundant number, since it is smaller than the sum of its proper divisors (669565646112).

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

209728780800 is a wasteful number, since it uses less digits than its factorization.

209728780800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10189 (or 10161 counting only the distinct ones).

The product of its (nonzero) digits is 903168, while the sum is 51.

It can be divided in two parts, 209728 and 780800, that added together give a triangular number (990528 = T₁₄₀₇).

The spelling of 209728780800 in words is "two hundred nine billion, seven hundred twenty-eight million, seven hundred eighty thousand, eight hundred".