21003323220021 has 16 divisors (see below), whose sum is σ = 28083200487680. Its totient is φ = 13962880543680.

The previous prime is 21003323220007. The next prime is 21003323220023. The reversal of 21003323220021 is 12002232330012.

It is a happy number.

It is not a de Polignac number, because 21003323220021 - 2⁹ = 21003323219509 is a prime.

It is a super-2 number, since 2×21003323220021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21003323220021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003323220023) 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, 4541350 + ... + 7913943.

It is an arithmetic number, because the mean of its divisors is an integer number (1755200030480).

Almost surely, 2^{21003323220021} is an apocalyptic number.

It is an amenable number.

21003323220021 is a deficient number, since it is larger than the sum of its proper divisors (7079877267659).

21003323220021 is a wasteful number, since it uses less digits than its factorization.

21003323220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12456876.

The product of its (nonzero) digits is 864, while the sum is 21.

Adding to 21003323220021 its reverse (12002232330012), we get a palindrome (33005555550033).

The spelling of 21003323220021 in words is "twenty-one trillion, three billion, three hundred twenty-three million, two hundred twenty thousand, twenty-one".