20906221 has 16 divisors (see below), whose sum is σ = 25017984. Its totient is φ = 17095104.

The previous prime is 20906203. The next prime is 20906227. The reversal of 20906221 is 12260902.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 20906221 - 2¹¹ = 20904173 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20906192 and 20906201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20906227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12966 + ... + 14488.

It is an arithmetic number, because the mean of its divisors is an integer number (1563624).

Almost surely, 2^20906221 is an apocalyptic number.

It is an amenable number.

20906221 is a deficient number, since it is larger than the sum of its proper divisors (4111763).

20906221 is a wasteful number, since it uses less digits than its factorization.

20906221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1620.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 20906221 is about 4572.3321182959. The cubic root of 20906221 is about 275.4811236042.

The spelling of 20906221 in words is "twenty million, nine hundred six thousand, two hundred twenty-one".