21012011121 has 4 divisors (see below), whose sum is σ = 28016014832. Its totient is φ = 14008007412.

The previous prime is 21012011093. The next prime is 21012011143. The reversal of 21012011121 is 12111021012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21012011121 - 2¹⁷ = 21011880049 is a prime.

It is a super-2 number, since 2×21012011121² (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 = 21012011097 and 21012011106.

It is not an unprimeable number, because it can be changed into a prime (21012011191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3502001851 + ... + 3502001856.

It is an arithmetic number, because the mean of its divisors is an integer number (7004003708).

Almost surely, 2^21012011121 is an apocalyptic number.

It is an amenable number.

21012011121 is a deficient number, since it is larger than the sum of its proper divisors (7004003711).

21012011121 is an equidigital number, since it uses as much as digits as its factorization.

21012011121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7004003710.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21012011121 its reverse (12111021012), we get a palindrome (33123032133).

The spelling of 21012011121 in words is "twenty-one billion, twelve million, eleven thousand, one hundred twenty-one".