21212353 has 2 divisors, whose sum is σ = 21212354. Its totient is φ = 21212352.

The previous prime is 21212297. The next prime is 21212423. The reversal of 21212353 is 35321212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20178064 + 1034289 = 4492^2 + 1017^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212353 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212353.

It is not a weakly prime, because it can be changed into another prime (21212453) by changing a digit.

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 as a sum of consecutive naturals, namely, 10606176 + 10606177.

It is an arithmetic number, because the mean of its divisors is an integer number (10606177).

Almost surely, 2^21212353 is an apocalyptic number.

It is an amenable number.

21212353 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212353 is an equidigital number, since it uses as much as digits as its factorization.

21212353 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 360, while the sum is 19.

The square root of 21212353 is about 4605.6870280122. The cubic root of 21212353 is about 276.8192463326.

Adding to 21212353 its reverse (35321212), we get a palindrome (56533565).

The spelling of 21212353 in words is "twenty-one million, two hundred twelve thousand, three hundred fifty-three".