20721140 has 48 divisors (see below), whose sum is σ = 48009024. Its totient is φ = 7449600.

The previous prime is 20721133. The next prime is 20721143. The reversal of 20721140 is 4112702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20721143) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20855 + ... + 21825.

It is an arithmetic number, because the mean of its divisors is an integer number (1000188).

Almost surely, 2^20721140 is an apocalyptic number.

20721140 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 20721140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24004512).

20721140 is an abundant number, since it is smaller than the sum of its proper divisors (27287884).

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

20721140 is a wasteful number, since it uses less digits than its factorization.

20721140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1088 (or 1086 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 20721140 is about 4552.0478907850. The cubic root of 20721140 is about 274.6657757797.

Adding to 20721140 its reverse (4112702), we get a palindrome (24833842).

The spelling of 20721140 in words is "twenty million, seven hundred twenty-one thousand, one hundred forty".