209128788 has 72 divisors (see below), whose sum is σ = 601788096. Its totient is φ = 60614400.

The previous prime is 209128783. The next prime is 209128807. The reversal of 209128788 is 887821902.

It is a happy number.

209128788 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209128783) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2373 + ... + 20588.

It is an arithmetic number, because the mean of its divisors is an integer number (8358168).

Almost surely, 2^209128788 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 209128788, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (300894048).

209128788 is an abundant number, since it is smaller than the sum of its proper divisors (392659308).

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

209128788 is a wasteful number, since it uses less digits than its factorization.

209128788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23005 (or 23000 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 209128788 is about 14461.2858349457. The cubic root of 209128788 is about 593.5690851507.

The spelling of 209128788 in words is "two hundred nine million, one hundred twenty-eight thousand, seven hundred eighty-eight".