21032403 has 16 divisors (see below), whose sum is σ = 32148480. Its totient is φ = 11981376.

The previous prime is 21032399. The next prime is 21032437. The reversal of 21032403 is 30423012.

It is not a de Polignac number, because 21032403 - 2² = 21032399 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21032483) 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 15 ways as a sum of consecutive naturals, for example, 6343 + ... + 9071.

It is an arithmetic number, because the mean of its divisors is an integer number (2009280).

Almost surely, 2^21032403 is an apocalyptic number.

21032403 is a deficient number, since it is larger than the sum of its proper divisors (11116077).

21032403 is a wasteful number, since it uses less digits than its factorization.

21032403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3106.

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21032403 is about 4586.1097893531. The cubic root of 21032403 is about 276.0342453832.

Adding to 21032403 its reverse (30423012), we get a palindrome (51455415).

The spelling of 21032403 in words is "twenty-one million, thirty-two thousand, four hundred three".