21001321321103 has 16 divisors (see below), whose sum is σ = 21640120778496. Its totient is φ = 20369459577600.

The previous prime is 21001321321073. The next prime is 21001321321121. The reversal of 21001321321103 is 30112312310012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21001321321103 - 2¹⁰ = 21001321320079 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001321321133) 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, 16817951 + ... + 18023487.

It is an arithmetic number, because the mean of its divisors is an integer number (1352507548656).

Almost surely, 2^{21001321321103} is an apocalyptic number.

21001321321103 is a deficient number, since it is larger than the sum of its proper divisors (638799457393).

21001321321103 is a wasteful number, since it uses less digits than its factorization.

21001321321103 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1208414.

The product of its (nonzero) digits is 216, while the sum is 20.

Adding to 21001321321103 its reverse (30112312310012), we get a palindrome (51113633631115).

The spelling of 21001321321103 in words is "twenty-one trillion, one billion, three hundred twenty-one million, three hundred twenty-one thousand, one hundred three".