21212108 has 24 divisors (see below), whose sum is σ = 38782800. Its totient is φ = 10138688.

The previous prime is 21212101. The next prime is 21212111. The reversal of 21212108 is 80121212.

It is a happy number.

It is a super-3 number, since 3×21212108³ (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, 11558 + ... + 13266.

It is an arithmetic number, because the mean of its divisors is an integer number (1615950).

Almost surely, 2^21212108 is an apocalyptic number.

It is an amenable number.

21212108 is a deficient number, since it is larger than the sum of its proper divisors (17570692).

21212108 is a wasteful number, since it uses less digits than its factorization.

21212108 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1849 (or 1847 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 21212108 is about 4605.6604303835. The cubic root of 21212108 is about 276.8181805861.

The spelling of 21212108 in words is "twenty-one million, two hundred twelve thousand, one hundred eight".