20866221 has 16 divisors (see below), whose sum is σ = 32257920. Its totient is φ = 13305600.

The previous prime is 20866211. The next prime is 20866229. The reversal of 20866221 is 12266802.

It is not a de Polignac number, because 20866221 - 2⁵ = 20866189 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20866229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16180 + ... + 17421.

It is an arithmetic number, because the mean of its divisors is an integer number (2016120).

Almost surely, 2^20866221 is an apocalyptic number.

It is an amenable number.

20866221 is a deficient number, since it is larger than the sum of its proper divisors (11391699).

20866221 is a wasteful number, since it uses less digits than its factorization.

20866221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33633 (or 33627 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 20866221 is about 4567.9558885786. The cubic root of 20866221 is about 275.3053181959.

The spelling of 20866221 in words is "twenty million, eight hundred sixty-six thousand, two hundred twenty-one".