21203120 has 40 divisors (see below), whose sum is σ = 49778064. Its totient is φ = 8398592.

The previous prime is 21203113. The next prime is 21203123. The reversal of 21203120 is 2130212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (21203123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7322 + ... + 9798.

Almost surely, 2^21203120 is an apocalyptic number.

21203120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21203120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24889032).

21203120 is an abundant number, since it is smaller than the sum of its proper divisors (28574944).

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

21203120 is a wasteful number, since it uses less digits than its factorization.

21203120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2597 (or 2591 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21203120 is about 4604.6845711731. The cubic root of 21203120 is about 276.7790772384.

Adding to 21203120 its reverse (2130212), we get a palindrome (23333332).

The spelling of 21203120 in words is "twenty-one million, two hundred three thousand, one hundred twenty".