21212106 has 16 divisors (see below), whose sum is σ = 42580704. Its totient is φ = 7044624.

The previous prime is 21212101. The next prime is 21212111. The reversal of 21212106 is 60121212.

It is an interprime number because it is at equal distance from previous prime (21212101) and next prime (21212111).

It is a super-3 number, since 3×21212106³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21212101) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 4720 + ... + 8043.

It is an arithmetic number, because the mean of its divisors is an integer number (2661294).

Almost surely, 2^21212106 is an apocalyptic number.

21212106 is an abundant number, since it is smaller than the sum of its proper divisors (21368598).

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

21212106 is a wasteful number, since it uses less digits than its factorization.

21212106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13045.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 21212106 is about 4605.6602132593. The cubic root of 21212106 is about 276.8181718861.

Adding to 21212106 its reverse (60121212), we get a palindrome (81333318).

The spelling of 21212106 in words is "twenty-one million, two hundred twelve thousand, one hundred six".