20845213 has 4 divisors (see below), whose sum is σ = 22071420. Its totient is φ = 19619008.

The previous prime is 20845207. The next prime is 20845217. The reversal of 20845213 is 31254802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31254802 = 2 ⋅15627401.

It can be written as a sum of positive squares in 2 ways, for example, as 6692569 + 14152644 = 2587^2 + 3762^2 .

It is a cyclic number.

It is not a de Polignac number, because 20845213 - 2⁹ = 20844701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20845217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 613078 + ... + 613111.

It is an arithmetic number, because the mean of its divisors is an integer number (5517855).

Almost surely, 2^20845213 is an apocalyptic number.

It is an amenable number.

20845213 is a deficient number, since it is larger than the sum of its proper divisors (1226207).

20845213 is a wasteful number, since it uses less digits than its factorization.

20845213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1226206.

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 20845213 is about 4565.6558126955. The cubic root of 20845213 is about 275.2128951967.

The spelling of 20845213 in words is "twenty million, eight hundred forty-five thousand, two hundred thirteen".