20900221 has 2 divisors, whose sum is σ = 20900222. Its totient is φ = 20900220.

The previous prime is 20900189. The next prime is 20900239. The reversal of 20900221 is 12200902.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20115225 + 784996 = 4485^2 + 886^2 .

It is a cyclic number.

It is not a de Polignac number, because 20900221 - 2⁵ = 20900189 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20900195 and 20900204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20900821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10450110 + 10450111.

It is an arithmetic number, because the mean of its divisors is an integer number (10450111).

Almost surely, 2^20900221 is an apocalyptic number.

It is an amenable number.

20900221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20900221 is an equidigital number, since it uses as much as digits as its factorization.

20900221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 20900221 is about 4571.6759508959. The cubic root of 20900221 is about 275.4547670970.

The spelling of 20900221 in words is "twenty million, nine hundred thousand, two hundred twenty-one".