20135221 has 2 divisors, whose sum is σ = 20135222. Its totient is φ = 20135220.

The previous prime is 20135207. The next prime is 20135239. The reversal of 20135221 is 12253102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20124196 + 11025 = 4486^2 + 105^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20135221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20135195 and 20135204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20135261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10067610 + 10067611.

It is an arithmetic number, because the mean of its divisors is an integer number (10067611).

Almost surely, 2^20135221 is an apocalyptic number.

It is an amenable number.

20135221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20135221 is an equidigital number, since it uses as much as digits as its factorization.

20135221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 20135221 is about 4487.2286547489. The cubic root of 20135221 is about 272.0521319122.

Adding to 20135221 its reverse (12253102), we get a palindrome (32388323).

The spelling of 20135221 in words is "twenty million, one hundred thirty-five thousand, two hundred twenty-one".