20728400 has 120 divisors (see below), whose sum is σ = 62180544. Its totient is φ = 6451200.

The previous prime is 20728387. The next prime is 20728403. The reversal of 20728400 is 482702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20728403) 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, 30464 + ... + 31136.

Almost surely, 2^20728400 is an apocalyptic number.

20728400 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 20728400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31090272).

20728400 is an abundant number, since it is smaller than the sum of its proper divisors (41452144).

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

20728400 is a wasteful number, since it uses less digits than its factorization.

20728400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 709 (or 698 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 23.

The square root of 20728400 is about 4552.8452642276. The cubic root of 20728400 is about 274.6978499592.

The spelling of 20728400 in words is "twenty million, seven hundred twenty-eight thousand, four hundred".