21120221122121 has 6 divisors (see below), whose sum is σ = 23214788506266. Its totient is φ = 19200201020000.

The previous prime is 21120221122111. The next prime is 21120221122123. The reversal of 21120221122121 is 12122112202112.

It can be written as a sum of positive squares in only one way, i.e., 18377683086400 + 2742538035721 = 4286920^2 + 1656061^2 .

It is not a de Polignac number, because 21120221122121 - 2¹⁸ = 21120220859977 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120221122093 and 21120221122102.

It is not an unprimeable number, because it can be changed into a prime (21120221122123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87273640880 + ... + 87273641121.

It is an arithmetic number, because the mean of its divisors is an integer number (3869131417711).

Almost surely, 2^{21120221122121} is an apocalyptic number.

It is an amenable number.

21120221122121 is a deficient number, since it is larger than the sum of its proper divisors (2094567384145).

21120221122121 is a wasteful number, since it uses less digits than its factorization.

21120221122121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174547282023 (or 174547282012 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 20.

Adding to 21120221122121 its reverse (12122112202112), we get a palindrome (33242333324233).

The spelling of 21120221122121 in words is "twenty-one trillion, one hundred twenty billion, two hundred twenty-one million, one hundred twenty-two thousand, one hundred twenty-one".