18203813 has 4 divisors (see below), whose sum is σ = 18254880. Its totient is φ = 18152748.

The previous prime is 18203743. The next prime is 18203819. The reversal of 18203813 is 31830281.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 31830281 = 7 ⋅4547183.

It is a cyclic number.

It is not a de Polignac number, because 18203813 - 2¹² = 18199717 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 (18203819) 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 in 3 ways as a sum of consecutive naturals, for example, 24995 + ... + 25712.

It is an arithmetic number, because the mean of its divisors is an integer number (4563720).

Almost surely, 2^18203813 is an apocalyptic number.

It is an amenable number.

18203813 is a deficient number, since it is larger than the sum of its proper divisors (51067).

18203813 is an equidigital number, since it uses as much as digits as its factorization.

18203813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51066.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 18203813 is about 4266.5926686291. The cubic root of 18203813 is about 263.0595796722.

The spelling of 18203813 in words is "eighteen million, two hundred three thousand, eight hundred thirteen".