21212308 has 24 divisors (see below), whose sum is σ = 41269760. Its totient is φ = 9473760.

The previous prime is 21212297. The next prime is 21212353. The reversal of 21212308 is 80321212.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 4968 + ... + 8191.

Almost surely, 2^21212308 is an apocalyptic number.

It is an amenable number.

21212308 is a deficient number, since it is larger than the sum of its proper divisors (20057452).

21212308 is a wasteful number, since it uses less digits than its factorization.

21212308 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13207 (or 13205 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 21212308 is about 4605.6821427450. The cubic root of 21212308 is about 276.8190505839.

The spelling of 21212308 in words is "twenty-one million, two hundred twelve thousand, three hundred eight".