21212099 has 2 divisors, whose sum is σ = 21212100. Its totient is φ = 21212098.

The previous prime is 21212089. The next prime is 21212101. The reversal of 21212099 is 99021212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21212099 - 2⁴ = 21212083 is a prime.

It is a super-3 number, since 3×21212099³ (a number of 23 digits) contains 333 as substring.

Together with 21212101, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21212089) 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 as a sum of consecutive naturals, namely, 10606049 + 10606050.

It is an arithmetic number, because the mean of its divisors is an integer number (10606050).

Almost surely, 2^21212099 is an apocalyptic number.

21212099 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212099 is an equidigital number, since it uses as much as digits as its factorization.

21212099 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 21212099 is about 4605.6594533248. The cubic root of 21212099 is about 276.8181414360.

The spelling of 21212099 in words is "twenty-one million, two hundred twelve thousand, ninety-nine".