20405145 has 16 divisors (see below), whose sum is σ = 34367040. Its totient is φ = 10309824.

The previous prime is 20405141. The next prime is 20405153. The reversal of 20405145 is 54150402.

It is not a de Polignac number, because 20405145 - 2² = 20405141 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20405141) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35514 + ... + 36083.

It is an arithmetic number, because the mean of its divisors is an integer number (2147940).

Almost surely, 2^20405145 is an apocalyptic number.

It is an amenable number.

20405145 is a deficient number, since it is larger than the sum of its proper divisors (13961895).

20405145 is a wasteful number, since it uses less digits than its factorization.

20405145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71624.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 20405145 is about 4517.2054414206. The cubic root of 20405145 is about 273.2624105434.

Adding to 20405145 its reverse (54150402), we get a palindrome (74555547).

The spelling of 20405145 in words is "twenty million, four hundred five thousand, one hundred forty-five".