20565221 has 8 divisors (see below), whose sum is σ = 20994624. Its totient is φ = 20139840.

The previous prime is 20565211. The next prime is 20565247. The reversal of 20565221 is 12256502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20565221 - 2⁶ = 20565157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20565211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10685 + ... + 12461.

It is an arithmetic number, because the mean of its divisors is an integer number (2624328).

Almost surely, 2^20565221 is an apocalyptic number.

It is an amenable number.

20565221 is a deficient number, since it is larger than the sum of its proper divisors (429403).

20565221 is a wasteful number, since it uses less digits than its factorization.

20565221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2011.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 20565221 is about 4534.8893040514. The cubic root of 20565221 is about 273.9751207275.

The spelling of 20565221 in words is "twenty million, five hundred sixty-five thousand, two hundred twenty-one".