21011323111 has 4 divisors (see below), whose sum is σ = 22247283312. Its totient is φ = 19775362912.

The previous prime is 21011323007. The next prime is 21011323117. The reversal of 21011323111 is 11132311012.

It is a happy number.

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 21011323111 - 2¹¹ = 21011321063 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011323117) 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, 617980075 + ... + 617980108.

It is an arithmetic number, because the mean of its divisors is an integer number (5561820828).

Almost surely, 2^21011323111 is an apocalyptic number.

21011323111 is a deficient number, since it is larger than the sum of its proper divisors (1235960201).

21011323111 is a wasteful number, since it uses less digits than its factorization.

21011323111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1235960200.

The product of its (nonzero) digits is 36, while the sum is 16.

Adding to 21011323111 its reverse (11132311012), we get a palindrome (32143634123).

The spelling of 21011323111 in words is "twenty-one billion, eleven million, three hundred twenty-three thousand, one hundred eleven".