21045206 has 24 divisors (see below), whose sum is σ = 39548880. Its totient is φ = 8325072.

The previous prime is 21045197. The next prime is 21045229. The reversal of 21045206 is 60254012.

It is a happy number.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 6986 + ... + 9533.

It is an arithmetic number, because the mean of its divisors is an integer number (1647870).

Almost surely, 2^21045206 is an apocalyptic number.

21045206 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21045206 is a deficient number, since it is larger than the sum of its proper divisors (18503674).

21045206 is a wasteful number, since it uses less digits than its factorization.

21045206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16548 (or 16541 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21045206 is about 4587.5054223401. The cubic root of 21045206 is about 276.0902438916.

Adding to 21045206 its reverse (60254012), we get a palindrome (81299218).

The spelling of 21045206 in words is "twenty-one million, forty-five thousand, two hundred six".