21253003 has 4 divisors (see below), whose sum is σ = 21570280. Its totient is φ = 20935728.

The previous prime is 21252997. The next prime is 21253007. The reversal of 21253003 is 30035212.

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

It is a cyclic number.

It is not a de Polignac number, because 21253003 - 2⁵ = 21252971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21253007) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 158538 + ... + 158671.

It is an arithmetic number, because the mean of its divisors is an integer number (5392570).

Almost surely, 2^21253003 is an apocalyptic number.

21253003 is a deficient number, since it is larger than the sum of its proper divisors (317277).

21253003 is an equidigital number, since it uses as much as digits as its factorization.

21253003 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317276.

The product of its (nonzero) digits is 180, while the sum is 16.

The square root of 21253003 is about 4610.0979382221. The cubic root of 21253003 is about 276.9959597477.

Adding to 21253003 its reverse (30035212), we get a palindrome (51288215).

The spelling of 21253003 in words is "twenty-one million, two hundred fifty-three thousand, three".