21020203 has 4 divisors (see below), whose sum is σ = 21114688. Its totient is φ = 20925720.

The previous prime is 21020161. The next prime is 21020227. The reversal of 21020203 is 30202012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21020203 is a prime.

It is a super-2 number, since 2×21020203² = 883697868322418, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21020203.

It is not an unprimeable number, because it can be changed into a prime (21020303) 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, 46908 + ... + 47353.

It is an arithmetic number, because the mean of its divisors is an integer number (5278672).

Almost surely, 2^21020203 is an apocalyptic number.

21020203 is a deficient number, since it is larger than the sum of its proper divisors (94485).

21020203 is an equidigital number, since it uses as much as digits as its factorization.

21020203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94484.

The product of its (nonzero) digits is 24, while the sum is 10.

The square root of 21020203 is about 4584.7794930618. The cubic root of 21020203 is about 275.9808631624.

Adding to 21020203 its reverse (30202012), we get a palindrome (51222215).

The spelling of 21020203 in words is "twenty-one million, twenty thousand, two hundred three".