21446009 has 4 divisors (see below), whose sum is σ = 23095716. Its totient is φ = 19796304.

The previous prime is 21445981. The next prime is 21446039. The reversal of 21446009 is 90064412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5221225 + 16224784 = 2285^2 + 4028^2 .

It is a cyclic number.

It is not a de Polignac number, because 21446009 - 2¹⁶ = 21380473 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21446039) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 824834 + ... + 824859.

It is an arithmetic number, because the mean of its divisors is an integer number (5773929).

Almost surely, 2^21446009 is an apocalyptic number.

It is an amenable number.

21446009 is a deficient number, since it is larger than the sum of its proper divisors (1649707).

21446009 is a wasteful number, since it uses less digits than its factorization.

21446009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1649706.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 21446009 is about 4630.9835888286. The cubic root of 21446009 is about 277.8319335063.

The spelling of 21446009 in words is "twenty-one million, four hundred forty-six thousand, nine".