21220613 has 2 divisors, whose sum is σ = 21220614. Its totient is φ = 21220612.

The previous prime is 21220601. The next prime is 21220627. The reversal of 21220613 is 31602212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19775809 + 1444804 = 4447^2 + 1202^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220613 - 2⁴ = 21220597 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21220591 and 21220600.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220313) 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, 10610306 + 10610307.

It is an arithmetic number, because the mean of its divisors is an integer number (10610307).

Almost surely, 2^21220613 is an apocalyptic number.

It is an amenable number.

21220613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220613 is an equidigital number, since it uses as much as digits as its factorization.

21220613 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21220613 is about 4606.5836582005. The cubic root of 21220613 is about 276.8551724154.

Adding to 21220613 its reverse (31602212), we get a palindrome (52822825).

The spelling of 21220613 in words is "twenty-one million, two hundred twenty thousand, six hundred thirteen".