21010101121 has 4 divisors (see below), whose sum is σ = 21014489412. Its totient is φ = 21005712832.

The previous prime is 21010101097. The next prime is 21010101139. The reversal of 21010101121 is 12110101012.

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 7891834896 + 13118266225 = 88836^2 + 114535^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010101121 - 2³³ = 12420166529 is a prime.

It is a super-2 number, since 2×21010101121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010101098 and 21010101107.

It is not an unprimeable number, because it can be changed into a prime (21010101191) 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, 2186956 + ... + 2196541.

It is an arithmetic number, because the mean of its divisors is an integer number (5253622353).

Almost surely, 2^21010101121 is an apocalyptic number.

It is an amenable number.

21010101121 is a deficient number, since it is larger than the sum of its proper divisors (4388291).

21010101121 is an equidigital number, since it uses as much as digits as its factorization.

21010101121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4388290.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21010101121 its reverse (12110101012), we get a palindrome (33120202133).

The spelling of 21010101121 in words is "twenty-one billion, ten million, one hundred one thousand, one hundred twenty-one".