20218403 has 4 divisors (see below), whose sum is σ = 21097488. Its totient is φ = 19339320.

The previous prime is 20218381. The next prime is 20218411. The reversal of 20218403 is 30481202.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 20218403 - 2¹⁴ = 20202019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20218433) 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, 439508 + ... + 439553.

It is an arithmetic number, because the mean of its divisors is an integer number (5274372).

Almost surely, 2^20218403 is an apocalyptic number.

20218403 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

20218403 is a deficient number, since it is larger than the sum of its proper divisors (879085).

20218403 is an equidigital number, since it uses as much as digits as its factorization.

20218403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 879084.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 20218403 is about 4496.4878516460. The cubic root of 20218403 is about 272.4262483125.

Adding to 20218403 its reverse (30481202), we get a palindrome (50699605).

The spelling of 20218403 in words is "twenty million, two hundred eighteen thousand, four hundred three".