21212449 has 2 divisors, whose sum is σ = 21212450. Its totient is φ = 21212448.

The previous prime is 21212431. The next prime is 21212453. The reversal of 21212449 is 94421212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14745600 + 6466849 = 3840^2 + 2543^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212449 - 2²¹ = 19115297 is a prime.

It is not a weakly prime, because it can be changed into another prime (21212489) 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, 10606224 + 10606225.

It is an arithmetic number, because the mean of its divisors is an integer number (10606225).

Almost surely, 2^21212449 is an apocalyptic number.

It is an amenable number.

21212449 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212449 is an equidigital number, since it uses as much as digits as its factorization.

21212449 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 25.

The square root of 21212449 is about 4605.6974498983. The cubic root of 21212449 is about 276.8196639290.

The spelling of 21212449 in words is "twenty-one million, two hundred twelve thousand, four hundred forty-nine".