21253403 has 8 divisors (see below), whose sum is σ = 22249728. Its totient is φ = 20263144.

The previous prime is 21253373. The next prime is 21253423. The reversal of 21253403 is 30435212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21253403 - 2⁶ = 21253339 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21253423) 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 7 ways as a sum of consecutive naturals, for example, 6650 + ... + 9312.

It is an arithmetic number, because the mean of its divisors is an integer number (2781216).

Almost surely, 2^21253403 is an apocalyptic number.

21253403 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21253403 is a deficient number, since it is larger than the sum of its proper divisors (996325).

21253403 is a wasteful number, since it uses less digits than its factorization.

21253403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3033.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21253403 is about 4610.1413210443. The cubic root of 21253403 is about 276.9976975050.

Adding to 21253403 its reverse (30435212), we get a palindrome (51688615).

The spelling of 21253403 in words is "twenty-one million, two hundred fifty-three thousand, four hundred three".