20018813 has 4 divisors (see below), whose sum is σ = 20559900. Its totient is φ = 19477728.

The previous prime is 20018807. The next prime is 20018819. The reversal of 20018813 is 31881002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31881002 = 2 ⋅15940501.

It is an interprime number because it is at equal distance from previous prime (20018807) and next prime (20018819).

It can be written as a sum of positive squares in 2 ways, for example, as 14760964 + 5257849 = 3842^2 + 2293^2 .

It is a cyclic number.

It is not a de Polignac number, because 20018813 - 2¹⁴ = 20002429 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 (20018819) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 270488 + ... + 270561.

It is an arithmetic number, because the mean of its divisors is an integer number (5139975).

Almost surely, 2^20018813 is an apocalyptic number.

It is an amenable number.

20018813 is a deficient number, since it is larger than the sum of its proper divisors (541087).

20018813 is an equidigital number, since it uses as much as digits as its factorization.

20018813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 541086.

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 20018813 is about 4474.2388179443. The cubic root of 20018813 is about 271.5268455514.

Adding to 20018813 its reverse (31881002), we get a palindrome (51899815).

The spelling of 20018813 in words is "twenty million, eighteen thousand, eight hundred thirteen".