21201101021 has 4 divisors (see below), whose sum is σ = 21932173500. Its totient is φ = 20470028544.

The previous prime is 21201101003. The next prime is 21201101083. The reversal of 21201101021 is 12010110212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3401805625 + 17799295396 = 58325^2 + 133414^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201101021 - 2⁶ = 21201100957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201100993 and 21201101011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201101321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 365536196 + ... + 365536253.

It is an arithmetic number, because the mean of its divisors is an integer number (5483043375).

Almost surely, 2^21201101021 is an apocalyptic number.

It is an amenable number.

21201101021 is a deficient number, since it is larger than the sum of its proper divisors (731072479).

21201101021 is an equidigital number, since it uses as much as digits as its factorization.

21201101021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 731072478.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21201101021 its reverse (12010110212), we get a palindrome (33211211233).

The spelling of 21201101021 in words is "twenty-one billion, two hundred one million, one hundred one thousand, twenty-one".