21206353 has 16 divisors (see below), whose sum is σ = 25344000. Its totient is φ = 17364816.

The previous prime is 21206347. The next prime is 21206357. The reversal of 21206353 is 35360212.

It is not a de Polignac number, because 21206353 - 2¹³ = 21198161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21206357) 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 15 ways as a sum of consecutive naturals, for example, 13398 + ... + 14896.

It is an arithmetic number, because the mean of its divisors is an integer number (1584000).

Almost surely, 2^21206353 is an apocalyptic number.

It is an amenable number.

21206353 is a deficient number, since it is larger than the sum of its proper divisors (4137647).

21206353 is a wasteful number, since it uses less digits than its factorization.

21206353 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1596.

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 21206353 is about 4605.0356133259. The cubic root of 21206353 is about 276.7931440562.

Adding to 21206353 its reverse (35360212), we get a palindrome (56566565).

The spelling of 21206353 in words is "twenty-one million, two hundred six thousand, three hundred fifty-three".