20681872 has 40 divisors (see below), whose sum is σ = 42285240. Its totient is φ = 9795968.

The previous prime is 20681831. The next prime is 20681879. The reversal of 20681872 is 27818602.

It can be written as a sum of positive squares in 4 ways, for example, as 467856 + 20214016 = 684^2 + 4496^2 .

It is not an unprimeable number, because it can be changed into a prime (20681879) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 390198 + ... + 390250.

It is an arithmetic number, because the mean of its divisors is an integer number (1057131).

Almost surely, 2^20681872 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20681872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21142620).

20681872 is an abundant number, since it is smaller than the sum of its proper divisors (21603368).

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

20681872 is an frugal number, since it uses more digits than its factorization.

20681872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 20681872 is about 4547.7326218677. The cubic root of 20681872 is about 274.4921624875.

The spelling of 20681872 in words is "twenty million, six hundred eighty-one thousand, eight hundred seventy-two".