21203013 has 16 divisors (see below), whose sum is σ = 30735936. Its totient is φ = 12923520.

The previous prime is 21203011. The next prime is 21203023. The reversal of 21203013 is 31030212.

It is a happy number.

It is not a de Polignac number, because 21203013 - 2¹ = 21203011 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21203013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1633 + ... + 6713.

It is an arithmetic number, because the mean of its divisors is an integer number (1920996).

Almost surely, 2^21203013 is an apocalyptic number.

It is an amenable number.

21203013 is a deficient number, since it is larger than the sum of its proper divisors (9532923).

21203013 is a wasteful number, since it uses less digits than its factorization.

21203013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5204.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21203013 is about 4604.6729525559. The cubic root of 21203013 is about 276.7786116558.

Adding to 21203013 its reverse (31030212), we get a palindrome (52233225).

The spelling of 21203013 in words is "twenty-one million, two hundred three thousand, thirteen".