20728920 has 32 divisors (see below), whose sum is σ = 62187120. Its totient is φ = 5527680.

The previous prime is 20728919. The next prime is 20728921. The reversal of 20728920 is 2982702.

It is an interprime number because it is at equal distance from previous prime (20728919) and next prime (20728921).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20728921) 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, 86251 + ... + 86490.

Almost surely, 2^20728920 is an apocalyptic number.

20728920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20728920 is an abundant number, since it is smaller than the sum of its proper divisors (41458200).

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

20728920 is a wasteful number, since it uses less digits than its factorization.

20728920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172755 (or 172751 counting only the distinct ones).

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

The square root of 20728920 is about 4552.9023710157. The cubic root of 20728920 is about 274.7001469959.

The spelling of 20728920 in words is "twenty million, seven hundred twenty-eight thousand, nine hundred twenty".