21206266 has 8 divisors (see below), whose sum is σ = 32585364. Its totient is φ = 10344480.

The previous prime is 21206249. The next prime is 21206303. The reversal of 21206266 is 66260212.

It can be written as a sum of positive squares in 2 ways, for example, as 21022225 + 184041 = 4585^2 + 429^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 21206266.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 129225 + ... + 129388.

Almost surely, 2^21206266 is an apocalyptic number.

21206266 is a deficient number, since it is larger than the sum of its proper divisors (11379098).

21206266 is a wasteful number, since it uses less digits than its factorization.

21206266 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258656.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21206266 is about 4605.0261671352. The cubic root of 21206266 is about 276.7927655370.

Adding to 21206266 its reverse (66260212), we get a palindrome (87466478).

The spelling of 21206266 in words is "twenty-one million, two hundred six thousand, two hundred sixty-six".