20209728 has 112 divisors (see below), whose sum is σ = 66714624. Its totient is φ = 5245440.

The previous prime is 20209691. The next prime is 20209741. The reversal of 20209728 is 82790202.

It is a tau number, because it is divible by the number of its divisors (112).

It is a junction number, because it is equal to n+sod(n) for n = 20209695 and 20209704.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14101 + ... + 15467.

Almost surely, 2^20209728 is an apocalyptic number.

20209728 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 20209728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33357312).

20209728 is an abundant number, since it is smaller than the sum of its proper divisors (46504896).

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

20209728 is a wasteful number, since it uses less digits than its factorization.

20209728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1400 (or 1390 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 20209728 is about 4495.5231063804. The cubic root of 20209728 is about 272.3872799234.

The spelling of 20209728 in words is "twenty million, two hundred nine thousand, seven hundred twenty-eight".