20428855 has 4 divisors (see below), whose sum is σ = 24514632. Its totient is φ = 16343080.

The previous prime is 20428843. The next prime is 20428909. The reversal of 20428855 is 55882402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 55882402 = 2 ⋅27941201.

It is not a de Polignac number, because 20428855 - 2⁵ = 20428823 is a prime.

It is a super-2 number, since 2×20428855² = 834676233222050, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20428855.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2042881 + ... + 2042890.

It is an arithmetic number, because the mean of its divisors is an integer number (6128658).

Almost surely, 2^20428855 is an apocalyptic number.

20428855 is a deficient number, since it is larger than the sum of its proper divisors (4085777).

20428855 is an equidigital number, since it uses as much as digits as its factorization.

20428855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4085776.

The product of its (nonzero) digits is 25600, while the sum is 34.

The square root of 20428855 is about 4519.8290896891. The cubic root of 20428855 is about 273.3682097410.

The spelling of 20428855 in words is "twenty million, four hundred twenty-eight thousand, eight hundred fifty-five".