20644291 has 4 divisors (see below), whose sum is σ = 20982784. Its totient is φ = 20305800.

The previous prime is 20644237. The next prime is 20644303. The reversal of 20644291 is 19244602.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20644291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20644391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 169155 + ... + 169276.

It is an arithmetic number, because the mean of its divisors is an integer number (5245696).

Almost surely, 2^20644291 is an apocalyptic number.

20644291 is a deficient number, since it is larger than the sum of its proper divisors (338493).

20644291 is an equidigital number, since it uses as much as digits as its factorization.

20644291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338492.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 20644291 is about 4543.5989039527. The cubic root of 20644291 is about 274.3258019104.

Adding to 20644291 its reverse (19244602), we get a palindrome (39888893).

The spelling of 20644291 in words is "twenty million, six hundred forty-four thousand, two hundred ninety-one".