209809428 has 48 divisors (see below), whose sum is σ = 505397760. Its totient is φ = 67709664.

The previous prime is 209809417. The next prime is 209809451. The reversal of 209809428 is 824908902.

It is a self number, because there is not a number n which added to its sum of digits gives 209809428.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45225 + ... + 49647.

It is an arithmetic number, because the mean of its divisors is an integer number (10529120).

Almost surely, 2^209809428 is an apocalyptic number.

It is an amenable number.

209809428 is an abundant number, since it is smaller than the sum of its proper divisors (295588332).

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

209809428 is a wasteful number, since it uses less digits than its factorization.

209809428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4556 (or 4554 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 42.

The square root of 209809428 is about 14484.7998950624. The cubic root of 209809428 is about 594.2123400514.

The spelling of 209809428 in words is "two hundred nine million, eight hundred nine thousand, four hundred twenty-eight".