21000221222121 has 24 divisors (see below), whose sum is σ = 32118223910760. Its totient is φ = 13176511543296.

The previous prime is 21000221222111. The next prime is 21000221222131. The reversal of 21000221222121 is 12122212200012.

It is a happy number.

21000221222121 is a `hidden beast` number, since 2 + 100 + 0 + 221 + 222 + 121 = 666.

It is an interprime number because it is at equal distance from previous prime (21000221222111) and next prime (21000221222131).

It can be written as a sum of positive squares in 4 ways, for example, as 940473248400 + 20059747973721 = 969780^2 + 4478811^2 .

It is not a de Polignac number, because 21000221222121 - 2³⁷ = 20862782268649 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21000221222094 and 21000221222103.

It is not an unprimeable number, because it can be changed into a prime (21000221222111) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24000165 + ... + 24859773.

It is an arithmetic number, because the mean of its divisors is an integer number (1338259329615).

Almost surely, 2^{21000221222121} is an apocalyptic number.

It is an amenable number.

21000221222121 is a deficient number, since it is larger than the sum of its proper divisors (11118002688639).

21000221222121 is a wasteful number, since it uses less digits than its factorization.

21000221222121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1019305 (or 1019302 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21000221222121 its reverse (12122212200012), we get a palindrome (33122433422133).

The spelling of 21000221222121 in words is "twenty-one trillion, two hundred twenty-one million, two hundred twenty-two thousand, one hundred twenty-one".