21003012321 has 16 divisors (see below), whose sum is σ = 30340880064. Its totient is φ = 12871885824.

The previous prime is 21003012293. The next prime is 21003012353. The reversal of 21003012321 is 12321030012.

It is not a de Polignac number, because 21003012321 - 2¹³ = 21003004129 is a prime.

It is a super-2 number, since 2×21003012321² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21003012321.

It is not an unprimeable number, because it can be changed into a prime (21003012221) 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, 4786456 + ... + 4790841.

It is an arithmetic number, because the mean of its divisors is an integer number (1896305004).

Almost surely, 2^21003012321 is an apocalyptic number.

It is an amenable number.

21003012321 is a deficient number, since it is larger than the sum of its proper divisors (9337867743).

21003012321 is a wasteful number, since it uses less digits than its factorization.

21003012321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9577360.

The product of its (nonzero) digits is 72, while the sum is 15.

Adding to 21003012321 its reverse (12321030012), we get a palindrome (33324042333).

The spelling of 21003012321 in words is "twenty-one billion, three million, twelve thousand, three hundred twenty-one".