20405213 has 2 divisors, whose sum is σ = 20405214. Its totient is φ = 20405212.

The previous prime is 20405207. The next prime is 20405233. The reversal of 20405213 is 31250402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15507844 + 4897369 = 3938^2 + 2213^2 .

It is a cyclic number.

It is not a de Polignac number, because 20405213 - 2⁴ = 20405197 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20405191 and 20405200.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20405233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202606 + 10202607.

It is an arithmetic number, because the mean of its divisors is an integer number (10202607).

Almost surely, 2^20405213 is an apocalyptic number.

It is an amenable number.

20405213 is a deficient number, since it is larger than the sum of its proper divisors (1).

20405213 is an equidigital number, since it uses as much as digits as its factorization.

20405213 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 20405213 is about 4517.2129681918. The cubic root of 20405213 is about 273.2627140914.

Adding to 20405213 its reverse (31250402), we get a palindrome (51655615).

The spelling of 20405213 in words is "twenty million, four hundred five thousand, two hundred thirteen".