21012111011 has 4 divisors (see below), whose sum is σ = 21177560832. Its totient is φ = 20846661192.

The previous prime is 21012110953. The next prime is 21012111013. The reversal of 21012111011 is 11011121012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21012111011 - 2²² = 21007916707 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012110983 and 21012111001.

It is not an unprimeable number, because it can be changed into a prime (21012111013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82724720 + ... + 82724973.

It is an arithmetic number, because the mean of its divisors is an integer number (5294390208).

Almost surely, 2^21012111011 is an apocalyptic number.

21012111011 is a deficient number, since it is larger than the sum of its proper divisors (165449821).

21012111011 is a wasteful number, since it uses less digits than its factorization.

21012111011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165449820.

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 21012111011 its reverse (11011121012), we get a palindrome (32023232023).

It can be divided in two parts, 2101 and 2111011, that added together give a palindrome (2113112).

The spelling of 21012111011 in words is "twenty-one billion, twelve million, one hundred eleven thousand, eleven".