21067221 has 8 divisors (see below), whose sum is σ = 32102464. Its totient is φ = 12038400.

The previous prime is 21067213. The next prime is 21067229. The reversal of 21067221 is 12276012.

It is an interprime number because it is at equal distance from previous prime (21067213) and next prime (21067229).

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

It is not a de Polignac number, because 21067221 - 2³ = 21067213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 1003201 = 21067221 / (2 + 1 + 0 + 6 + 7 + 2 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21067229) 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 7 ways as a sum of consecutive naturals, for example, 501580 + ... + 501621.

It is an arithmetic number, because the mean of its divisors is an integer number (4012808).

Almost surely, 2^21067221 is an apocalyptic number.

21067221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21067221 is a deficient number, since it is larger than the sum of its proper divisors (11035243).

21067221 is a wasteful number, since it uses less digits than its factorization.

21067221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1003211.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21067221 is about 4589.9042473673. The cubic root of 21067221 is about 276.1864813046.

The spelling of 21067221 in words is "twenty-one million, sixty-seven thousand, two hundred twenty-one".