21011012011 has 16 divisors (see below), whose sum is σ = 25052295168. Its totient is φ = 17397417600.

The previous prime is 21011011997. The next prime is 21011012027. The reversal of 21011012011 is 11021011012.

It is a cyclic number.

It is not a de Polignac number, because 21011012011 - 2⁵ = 21011011979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011012311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1806435 + ... + 1818028.

It is an arithmetic number, because the mean of its divisors is an integer number (1565768448).

Almost surely, 2^21011012011 is an apocalyptic number.

21011012011 is a deficient number, since it is larger than the sum of its proper divisors (4041283157).

21011012011 is a wasteful number, since it uses less digits than its factorization.

21011012011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3624522.

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

Adding to 21011012011 its reverse (11021011012), we get a palindrome (32032023023).

Subtracting from 21011012011 its reverse (11021011012), we obtain a palindrome (9990000999).

The spelling of 21011012011 in words is "twenty-one billion, eleven million, twelve thousand, eleven".