21003225 has 24 divisors (see below), whose sum is σ = 34929312. Its totient is φ = 11136000.

The previous prime is 21003223. The next prime is 21003247. The reversal of 21003225 is 52230012.

It is not a de Polignac number, because 21003225 - 2¹ = 21003223 is a prime.

It is a super-2 number, since 2×21003225² = 882270920801250, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (21003223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13750 + ... + 15200.

It is an arithmetic number, because the mean of its divisors is an integer number (1455388).

Almost surely, 2^21003225 is an apocalyptic number.

21003225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21003225 is a deficient number, since it is larger than the sum of its proper divisors (13926087).

21003225 is a wasteful number, since it uses less digits than its factorization.

21003225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1657 (or 1652 counting only the distinct ones).

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

The square root of 21003225 is about 4582.9275577953. The cubic root of 21003225 is about 275.9065399794.

Adding to 21003225 its reverse (52230012), we get a palindrome (73233237).

The spelling of 21003225 in words is "twenty-one million, three thousand, two hundred twenty-five".