21049221 has 8 divisors (see below), whose sum is σ = 28092960. Its totient is φ = 14019152.

The previous prime is 21049219. The next prime is 21049241. The reversal of 21049221 is 12294012.

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 21049221 - 2¹ = 21049219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21049201) 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 7 ways as a sum of consecutive naturals, for example, 991 + ... + 6563.

It is an arithmetic number, because the mean of its divisors is an integer number (3511620).

Almost surely, 2^21049221 is an apocalyptic number.

It is an amenable number.

21049221 is a deficient number, since it is larger than the sum of its proper divisors (7043739).

21049221 is a wasteful number, since it uses less digits than its factorization.

21049221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6835.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 21049221 is about 4587.9430031333. The cubic root of 21049221 is about 276.1078002549.

It can be divided in two parts, 2104 and 9221, that added together give a triangular number (11325 = T₁₅₀).

The spelling of 21049221 in words is "twenty-one million, forty-nine thousand, two hundred twenty-one".