21000100002221 has 4 divisors (see below), whose sum is σ = 21000814296444. Its totient is φ = 20999385708000.

The previous prime is 21000100002169. The next prime is 21000100002229. The reversal of 21000100002221 is 12220000100012.

It is a happy number.

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 10363441792900 + 10636658209321 = 3219230^2 + 3261389^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000100002221 - 2¹⁸ = 21000099740077 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 (21000100002229) 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, 357103010 + ... + 357161811.

It is an arithmetic number, because the mean of its divisors is an integer number (5250203574111).

Almost surely, 2^{21000100002221} is an apocalyptic number.

It is an amenable number.

21000100002221 is a deficient number, since it is larger than the sum of its proper divisors (714294223).

21000100002221 is an equidigital number, since it uses as much as digits as its factorization.

21000100002221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 714294222.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21000100002221 its reverse (12220000100012), we get a palindrome (33220100102233).

The spelling of 21000100002221 in words is "twenty-one trillion, one hundred million, two thousand, two hundred twenty-one".