21064221 has 24 divisors (see below), whose sum is σ = 31755776. Its totient is φ = 13439520.

The previous prime is 21064193. The next prime is 21064231. The reversal of 21064221 is 12246012.

21064221 is a `hidden beast` number, since 2 + 1 + 0 + 642 + 21 = 666.

It is not a de Polignac number, because 21064221 - 2⁵ = 21064189 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21064194 and 21064203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21064231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28371 + ... + 29103.

Almost surely, 2^21064221 is an apocalyptic number.

It is an amenable number.

21064221 is a deficient number, since it is larger than the sum of its proper divisors (10691555).

21064221 is a wasteful number, since it uses less digits than its factorization.

21064221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 873 (or 870 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21064221 is about 4589.5774315290. The cubic root of 21064221 is about 276.1733709095.

The spelling of 21064221 in words is "twenty-one million, sixty-four thousand, two hundred twenty-one".