20523221 has 2 divisors, whose sum is σ = 20523222. Its totient is φ = 20523220.

The previous prime is 20523203. The next prime is 20523227. The reversal of 20523221 is 12232502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20151121 + 372100 = 4489^2 + 610^2 .

It is a cyclic number.

It is not a de Polignac number, because 20523221 - 2⁶ = 20523157 is a prime.

It is a super-3 number, since 3×20523221³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20523221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20523227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10261610 + 10261611.

It is an arithmetic number, because the mean of its divisors is an integer number (10261611).

Almost surely, 2^20523221 is an apocalyptic number.

It is an amenable number.

20523221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20523221 is an equidigital number, since it uses as much as digits as its factorization.

20523221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 20523221 is about 4530.2561737721. The cubic root of 20523221 is about 273.7884820418.

Adding to 20523221 its reverse (12232502), we get a palindrome (32755723).

The spelling of 20523221 in words is "twenty million, five hundred twenty-three thousand, two hundred twenty-one".