21052306 has 12 divisors (see below), whose sum is σ = 34710606. Its totient is φ = 9569120.

The previous prime is 21052301. The next prime is 21052331. The reversal of 21052306 is 60325012.

It is a happy number.

21052306 is nontrivially palindromic in base 15.

It can be written as a sum of positive squares in only one way, i.e., 15249025 + 5803281 = 3905^2 + 2409^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21052301) 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 5 ways as a sum of consecutive naturals, for example, 43255 + ... + 43738.

Almost surely, 2^21052306 is an apocalyptic number.

21052306 is a deficient number, since it is larger than the sum of its proper divisors (13658300).

21052306 is a wasteful number, since it uses less digits than its factorization.

21052306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87017 (or 87006 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21052306 is about 4588.2791981308. The cubic root of 21052306 is about 276.1212884968.

Adding to 21052306 its reverse (60325012), we get a palindrome (81377318).

The spelling of 21052306 in words is "twenty-one million, fifty-two thousand, three hundred six".