20818728 has 128 divisors (see below), whose sum is σ = 67680000. Its totient is φ = 5927040.

The previous prime is 20818649. The next prime is 20818739. The reversal of 20818728 is 82781802.

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 = 20818692 and 20818701.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 73948 + ... + 74228.

It is an arithmetic number, because the mean of its divisors is an integer number (528750).

Almost surely, 2^20818728 is an apocalyptic number.

20818728 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 20818728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33840000).

20818728 is an abundant number, since it is smaller than the sum of its proper divisors (46861272).

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

20818728 is a wasteful number, since it uses less digits than its factorization.

20818728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317 (or 293 counting only the distinct ones).

The product of its (nonzero) digits is 14336, while the sum is 36.

The square root of 20818728 is about 4562.7544312619. The cubic root of 20818728 is about 275.0962880450.

The spelling of 20818728 in words is "twenty million, eight hundred eighteen thousand, seven hundred twenty-eight".