20215720 has 128 divisors (see below), whose sum is σ = 57231360. Its totient is φ = 6266880.

The previous prime is 20215711. The next prime is 20215721. The reversal of 20215720 is 2751202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20215721) by changing a digit.

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, 147492 + ... + 147628.

It is an arithmetic number, because the mean of its divisors is an integer number (447120).

Almost surely, 2^20215720 is an apocalyptic number.

20215720 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 20215720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28615680).

20215720 is an abundant number, since it is smaller than the sum of its proper divisors (37015640).

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

20215720 is a wasteful number, since it uses less digits than its factorization.

20215720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203 (or 199 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 20215720 is about 4496.1894977859. The cubic root of 20215720 is about 272.4141973779.

Adding to 20215720 its reverse (2751202), we get a palindrome (22966922).

The spelling of 20215720 in words is "twenty million, two hundred fifteen thousand, seven hundred twenty".