20540221 has 16 divisors (see below), whose sum is σ = 22967280. Its totient is φ = 18247680.

The previous prime is 20540209. The next prime is 20540227. The reversal of 20540221 is 12204502.

It can be written as a sum of positive squares in 8 ways, for example, as 11902500 + 8637721 = 3450^2 + 2939^2 .

It is a cyclic number.

It is not a de Polignac number, because 20540221 - 2⁹ = 20539709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20540195 and 20540204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20540227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47221 + ... + 47653.

It is an arithmetic number, because the mean of its divisors is an integer number (1435455).

Almost surely, 2^20540221 is an apocalyptic number.

It is an amenable number.

20540221 is a deficient number, since it is larger than the sum of its proper divisors (2427059).

20540221 is a wasteful number, since it uses less digits than its factorization.

20540221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 576.

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 20540221 is about 4532.1320589762. The cubic root of 20540221 is about 273.8640569180.

Adding to 20540221 its reverse (12204502), we get a palindrome (32744723).

The spelling of 20540221 in words is "twenty million, five hundred forty thousand, two hundred twenty-one".