20928720 has 160 divisors (see below), whose sum is σ = 69995520. Its totient is φ = 5160960.

The previous prime is 20928707. The next prime is 20928757. The reversal of 20928720 is 2782902.

It is a super-2 number, since 2×20928720² = 876022641676800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

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, 215712 + ... + 215808.

It is an arithmetic number, because the mean of its divisors is an integer number (437472).

Almost surely, 2^20928720 is an apocalyptic number.

20928720 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 20928720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34997760).

20928720 is an abundant number, since it is smaller than the sum of its proper divisors (49066800).

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

20928720 is a wasteful number, since it uses less digits than its factorization.

20928720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 20928720 is about 4574.7917985412. The cubic root of 20928720 is about 275.5799112283.

The spelling of 20928720 in words is "twenty million, nine hundred twenty-eight thousand, seven hundred twenty".