21202023121 has 4 divisors (see below), whose sum is σ = 21411944244. Its totient is φ = 20992102000.

The previous prime is 21202023113. The next prime is 21202023137. The reversal of 21202023121 is 12132020212.

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 14027086096 + 7174937025 = 118436^2 + 84705^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202023121 - 2³ = 21202023113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202023095 and 21202023104.

It is not an unprimeable number, because it can be changed into a prime (21202053121) 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, 104960410 + ... + 104960611.

It is an arithmetic number, because the mean of its divisors is an integer number (5352986061).

Almost surely, 2^21202023121 is an apocalyptic number.

It is an amenable number.

21202023121 is a deficient number, since it is larger than the sum of its proper divisors (209921123).

21202023121 is a wasteful number, since it uses less digits than its factorization.

21202023121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209921122.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21202023121 its reverse (12132020212), we get a palindrome (33334043333).

The spelling of 21202023121 in words is "twenty-one billion, two hundred two million, twenty-three thousand, one hundred twenty-one".