21046209 has 8 divisors (see below), whose sum is σ = 28096992. Its totient is φ = 14013120.

The previous prime is 21046171. The next prime is 21046217. The reversal of 21046209 is 90264012.

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

It is not a de Polignac number, because 21046209 - 2⁹ = 21045697 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21046009) 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, 1339 + ... + 6624.

It is an arithmetic number, because the mean of its divisors is an integer number (3512124).

Almost surely, 2^21046209 is an apocalyptic number.

It is an amenable number.

21046209 is a deficient number, since it is larger than the sum of its proper divisors (7050783).

21046209 is an equidigital number, since it uses as much as digits as its factorization.

21046209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8847.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21046209 is about 4587.6147397095. The cubic root of 21046209 is about 276.0946299121.

The spelling of 21046209 in words is "twenty-one million, forty-six thousand, two hundred nine".