20420405 has 4 divisors (see below), whose sum is σ = 24504492. Its totient is φ = 16336320.

The previous prime is 20420377. The next prime is 20420443. The reversal of 20420405 is 50402402.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3659569 + 16760836 = 1913^2 + 4094^2 .

It is not a de Polignac number, because 20420405 - 2¹⁰ = 20419381 is a prime.

It is a Duffinian number.

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, 2042036 + ... + 2042045.

It is an arithmetic number, because the mean of its divisors is an integer number (6126123).

Almost surely, 2^20420405 is an apocalyptic number.

It is an amenable number.

20420405 is a deficient number, since it is larger than the sum of its proper divisors (4084087).

20420405 is an equidigital number, since it uses as much as digits as its factorization.

20420405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4084086.

The product of its (nonzero) digits is 320, while the sum is 17.

The square root of 20420405 is about 4518.8942231480. The cubic root of 20420405 is about 273.3305133888.

Adding to 20420405 its reverse (50402402), we get a palindrome (70822807).

The spelling of 20420405 in words is "twenty million, four hundred twenty thousand, four hundred five".