21203320 has 32 divisors (see below), whose sum is σ = 48139920. Its totient is φ = 8404480.

The previous prime is 21203317. The next prime is 21203341. The reversal of 21203320 is 2330212.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21203320.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2175 + ... + 6865.

Almost surely, 2^21203320 is an apocalyptic number.

21203320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21203320 is an abundant number, since it is smaller than the sum of its proper divisors (26936600).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21203320 is a wasteful number, since it uses less digits than its factorization.

21203320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4815 (or 4811 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 13.

The square root of 21203320 is about 4604.7062881361. The cubic root of 21203320 is about 276.7799474821.

Adding to 21203320 its reverse (2330212), we get a palindrome (23533532).

The spelling of 21203320 in words is "twenty-one million, two hundred three thousand, three hundred twenty".