21272213 has 2 divisors, whose sum is σ = 21272214. Its totient is φ = 21272212.

The previous prime is 21272189. The next prime is 21272269. The reversal of 21272213 is 31227212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21003889 + 268324 = 4583^2 + 518^2 .

It is a cyclic number.

It is not a de Polignac number, because 21272213 - 2⁶ = 21272149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23272213) 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, 10636106 + 10636107.

It is an arithmetic number, because the mean of its divisors is an integer number (10636107).

Almost surely, 2^21272213 is an apocalyptic number.

It is an amenable number.

21272213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21272213 is an equidigital number, since it uses as much as digits as its factorization.

21272213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 336, while the sum is 20.

The square root of 21272213 is about 4612.1809374742. The cubic root of 21272213 is about 277.0793909377.

Adding to 21272213 its reverse (31227212), we get a palindrome (52499425).

The spelling of 21272213 in words is "twenty-one million, two hundred seventy-two thousand, two hundred thirteen".