20556281 has 6 divisors (see below), whose sum is σ = 21836910. Its totient is φ = 19346816.

The previous prime is 20556269. The next prime is 20556299. The reversal of 20556281 is 18265502.

It can be written as a sum of positive squares in 3 ways, for example, as 5221225 + 15335056 = 2285^2 + 3916^2 .

It is not a de Polignac number, because 20556281 - 2¹⁸ = 20294137 is a prime.

It is a super-2 number, since 2×20556281² = 845121377101922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20516281) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35276 + ... + 35853.

It is an arithmetic number, because the mean of its divisors is an integer number (3639485).

Almost surely, 2^20556281 is an apocalyptic number.

It is an amenable number.

20556281 is a deficient number, since it is larger than the sum of its proper divisors (1280629).

20556281 is an equidigital number, since it uses as much as digits as its factorization.

20556281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71163 (or 71146 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 29.

The square root of 20556281 is about 4533.9035058104. The cubic root of 20556281 is about 273.9354146531.

The spelling of 20556281 in words is "twenty million, five hundred fifty-six thousand, two hundred eighty-one".