21101001012221 has 4 divisors (see below), whose sum is σ = 22724154936252. Its totient is φ = 19477847088192.

The previous prime is 21101001012167. The next prime is 21101001012229. The reversal of 21101001012221 is 12221010010112.

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 11336594724196 + 9764406288025 = 3366986^2 + 3124805^2 .

It is a cyclic number.

It is not a de Polignac number, because 21101001012221 - 2¹⁰ = 21101001011197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101001012196 and 21101001012205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101001012229) 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, 811576961996 + ... + 811576962021.

It is an arithmetic number, because the mean of its divisors is an integer number (5681038734063).

Almost surely, 2^{21101001012221} is an apocalyptic number.

It is an amenable number.

21101001012221 is a deficient number, since it is larger than the sum of its proper divisors (1623153924031).

21101001012221 is a wasteful number, since it uses less digits than its factorization.

21101001012221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1623153924030.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21101001012221 its reverse (12221010010112), we get a palindrome (33322011022333).

The spelling of 21101001012221 in words is "twenty-one trillion, one hundred one billion, one million, twelve thousand, two hundred twenty-one".