20409355 has 4 divisors (see below), whose sum is σ = 24491232. Its totient is φ = 16327480.

The previous prime is 20409353. The next prime is 20409371. The reversal of 20409355 is 55390402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 55390402 = 2 ⋅27695201.

It is not a de Polignac number, because 20409355 - 2¹ = 20409353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20409353) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 2040931 + ... + 2040940.

It is an arithmetic number, because the mean of its divisors is an integer number (6122808).

Almost surely, 2^20409355 is an apocalyptic number.

20409355 is a deficient number, since it is larger than the sum of its proper divisors (4081877).

20409355 is an equidigital number, since it uses as much as digits as its factorization.

20409355 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4081876.

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 20409355 is about 4517.6714134607. The cubic root of 20409355 is about 273.2812024647.

Adding to 20409355 its reverse (55390402), we get a palindrome (75799757).

The spelling of 20409355 in words is "twenty million, four hundred nine thousand, three hundred fifty-five".