209440728 has 96 divisors (see below), whose sum is σ = 672322560. Its totient is φ = 59836320.

The previous prime is 209440717. The next prime is 209440739. The reversal of 209440728 is 827044902.

209440728 is a `hidden beast` number, since 209 + 440 + 7 + 2 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (209440717) and next prime (209440739).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 209440692 and 209440701.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5913 + ... + 21303.

It is an arithmetic number, because the mean of its divisors is an integer number (7003360).

Almost surely, 2^209440728 is an apocalyptic number.

209440728 is a gapful number since it is divisible by the number (28) 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 209440728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (336161280).

209440728 is an abundant number, since it is smaller than the sum of its proper divisors (462881832).

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

209440728 is a wasteful number, since it uses less digits than its factorization.

209440728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15419 (or 15403 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 209440728 is about 14472.0671640233. The cubic root of 209440728 is about 593.8640643943.

The spelling of 209440728 in words is "two hundred nine million, four hundred forty thousand, seven hundred twenty-eight".