21133206 has 48 divisors (see below), whose sum is σ = 49037040. Its totient is φ = 6557760.

The previous prime is 21133153. The next prime is 21133213. The reversal of 21133206 is 60233112.

It is a super-2 number, since 2×21133206² = 893224791676872, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

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 23 ways as a sum of consecutive naturals, for example, 20356 + ... + 21368.

It is an arithmetic number, because the mean of its divisors is an integer number (1021605).

Almost surely, 2^21133206 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21133206, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24518520).

21133206 is an abundant number, since it is smaller than the sum of its proper divisors (27903834).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21133206 is a wasteful number, since it uses less digits than its factorization.

21133206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1101 (or 1098 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21133206 is about 4597.0866861524. The cubic root of 21133206 is about 276.4745302325.

Adding to 21133206 its reverse (60233112), we get a palindrome (81366318).

The spelling of 21133206 in words is "twenty-one million, one hundred thirty-three thousand, two hundred six".