20641405 has 4 divisors (see below), whose sum is σ = 24769692. Its totient is φ = 16513120.

The previous prime is 20641403. The next prime is 20641457. The reversal of 20641405 is 50414602.

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 8398404 + 12243001 = 2898^2 + 3499^2 .

It is not a de Polignac number, because 20641405 - 2¹ = 20641403 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20641403) 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 3 ways as a sum of consecutive naturals, for example, 2064136 + ... + 2064145.

It is an arithmetic number, because the mean of its divisors is an integer number (6192423).

Almost surely, 2^20641405 is an apocalyptic number.

It is an amenable number.

20641405 is a deficient number, since it is larger than the sum of its proper divisors (4128287).

20641405 is an equidigital number, since it uses as much as digits as its factorization.

20641405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4128286.

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 20641405 is about 4543.2813031993. The cubic root of 20641405 is about 274.3130180507.

The spelling of 20641405 in words is "twenty million, six hundred forty-one thousand, four hundred five".