20744281 has 4 divisors (see below), whose sum is σ = 20753572. Its totient is φ = 20734992.

The previous prime is 20744279. The next prime is 20744287. The reversal of 20744281 is 18244702.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 16160400 + 4583881 = 4020^2 + 2141^2 .

It is a cyclic number.

It is not a de Polignac number, because 20744281 - 2¹ = 20744279 is a prime.

It is a super-2 number, since 2×20744281² = 860650388413922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20744287) 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, 955 + ... + 6511.

It is an arithmetic number, because the mean of its divisors is an integer number (5188393).

Almost surely, 2^20744281 is an apocalyptic number.

It is an amenable number.

20744281 is a deficient number, since it is larger than the sum of its proper divisors (9291).

20744281 is an equidigital number, since it uses as much as digits as its factorization.

20744281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9290.

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 20744281 is about 4554.5890045096. The cubic root of 20744281 is about 274.7679850224.

Adding to 20744281 its reverse (18244702), we get a palindrome (38988983).

It can be divided in two parts, 20744 and 281, that added together give a square (21025 = 145²).

The spelling of 20744281 in words is "twenty million, seven hundred forty-four thousand, two hundred eighty-one".