21020101121 has 4 divisors (see below), whose sum is σ = 21044744532. Its totient is φ = 20995457712.

The previous prime is 21020101099. The next prime is 21020101127. The reversal of 21020101121 is 12110102012.

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 6992304400 + 14027796721 = 83620^2 + 118439^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020101121 - 2¹⁸ = 21019838977 is a prime.

It is a super-2 number, since 2×21020101121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020101127) 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, 12320426 + ... + 12322131.

It is an arithmetic number, because the mean of its divisors is an integer number (5261186133).

Almost surely, 2^21020101121 is an apocalyptic number.

It is an amenable number.

21020101121 is a deficient number, since it is larger than the sum of its proper divisors (24643411).

21020101121 is an equidigital number, since it uses as much as digits as its factorization.

21020101121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24643410.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21020101121 its reverse (12110102012), we get a palindrome (33130203133).

The spelling of 21020101121 in words is "twenty-one billion, twenty million, one hundred one thousand, one hundred twenty-one".