20428605 has 20 divisors (see below), whose sum is σ = 36620892. Its totient is φ = 10895040.

The previous prime is 20428601. The next prime is 20428613. The reversal of 20428605 is 50682402.

It can be written as a sum of positive squares in 2 ways, for example, as 13089924 + 7338681 = 3618^2 + 2709^2 .

It is not a de Polignac number, because 20428605 - 2² = 20428601 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20428601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 24816 + ... + 25625.

Almost surely, 2^20428605 is an apocalyptic number.

It is an amenable number.

20428605 is a deficient number, since it is larger than the sum of its proper divisors (16192287).

20428605 is an equidigital number, since it uses as much as digits as its factorization.

20428605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50458 (or 50449 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 20428605 is about 4519.8014336915. The cubic root of 20428605 is about 273.3670946135.

The spelling of 20428605 in words is "twenty million, four hundred twenty-eight thousand, six hundred five".