21203205 has 32 divisors (see below), whose sum is σ = 35596800. Its totient is φ = 10762752.

The previous prime is 21203197. The next prime is 21203213. The reversal of 21203205 is 50230212.

It is an interprime number because it is at equal distance from previous prime (21203197) and next prime (21203213).

It is not a de Polignac number, because 21203205 - 2³ = 21203197 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34057 + ... + 34673.

It is an arithmetic number, because the mean of its divisors is an integer number (1112400).

Almost surely, 2^21203205 is an apocalyptic number.

It is an amenable number.

21203205 is a deficient number, since it is larger than the sum of its proper divisors (14393595).

21203205 is a wasteful number, since it uses less digits than its factorization.

21203205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 733.

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 21203205 is about 4604.6938008949. The cubic root of 21203205 is about 276.7794470926.

Adding to 21203205 its reverse (50230212), we get a palindrome (71433417).

The spelling of 21203205 in words is "twenty-one million, two hundred three thousand, two hundred five".