20644271 has 4 divisors (see below), whose sum is σ = 21541872. Its totient is φ = 19746672.

The previous prime is 20644237. The next prime is 20644303. The reversal of 20644271 is 17244602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17244602 = 2 ⋅8622301.

It is a cyclic number.

It is not a de Polignac number, because 20644271 - 2¹⁸ = 20382127 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20644271.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20644471) 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, 448766 + ... + 448811.

It is an arithmetic number, because the mean of its divisors is an integer number (5385468).

Almost surely, 2^20644271 is an apocalyptic number.

20644271 is a deficient number, since it is larger than the sum of its proper divisors (897601).

20644271 is an equidigital number, since it uses as much as digits as its factorization.

20644271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 897600.

The product of its (nonzero) digits is 2688, while the sum is 26.

The square root of 20644271 is about 4543.5967030537. The cubic root of 20644271 is about 274.3257133223.

Adding to 20644271 its reverse (17244602), we get a palindrome (37888873).

The spelling of 20644271 in words is "twenty million, six hundred forty-four thousand, two hundred seventy-one".