20420728 has 24 divisors (see below), whose sum is σ = 38901600. Its totient is φ = 10049472.

The previous prime is 20420681. The next prime is 20420759. The reversal of 20420728 is 82702402.

It is a super-2 number, since 2×20420728² = 834012264099968, which contains 22 as substring.

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 5 ways as a sum of consecutive naturals, for example, 42393 + ... + 42871.

It is an arithmetic number, because the mean of its divisors is an integer number (1620900).

Almost surely, 2^20420728 is an apocalyptic number.

It is an amenable number.

20420728 is a deficient number, since it is larger than the sum of its proper divisors (18480872).

20420728 is an equidigital number, since it uses as much as digits as its factorization.

20420728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 631 (or 554 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 25.

The square root of 20420728 is about 4518.9299618383. The cubic root of 20420728 is about 273.3319545175.

The spelling of 20420728 in words is "twenty million, four hundred twenty thousand, seven hundred twenty-eight".