21203421 has 8 divisors (see below), whose sum is σ = 28389504. Its totient is φ = 14076480.

The previous prime is 21203419. The next prime is 21203431. The reversal of 21203421 is 12430212.

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

It is not a de Polignac number, because 21203421 - 2¹ = 21203419 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21203421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203431) 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 7 ways as a sum of consecutive naturals, for example, 13941 + ... + 15386.

It is an arithmetic number, because the mean of its divisors is an integer number (3548688).

Almost surely, 2^21203421 is an apocalyptic number.

It is an amenable number.

21203421 is a deficient number, since it is larger than the sum of its proper divisors (7186083).

21203421 is a wasteful number, since it uses less digits than its factorization.

21203421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29571.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21203421 is about 4604.7172551634. The cubic root of 21203421 is about 276.7803869530.

Adding to 21203421 its reverse (12430212), we get a palindrome (33633633).

The spelling of 21203421 in words is "twenty-one million, two hundred three thousand, four hundred twenty-one".