21011021111 has 8 divisors (see below), whose sum is σ = 22224881760. Its totient is φ = 19822188672.

The previous prime is 21011021107. The next prime is 21011021113. The reversal of 21011021111 is 11112011012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21011021111 - 2² = 21011021107 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011021092 and 21011021101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011021113) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6255326 + ... + 6258683.

It is an arithmetic number, because the mean of its divisors is an integer number (2778110220).

Almost surely, 2^21011021111 is an apocalyptic number.

21011021111 is a deficient number, since it is larger than the sum of its proper divisors (1213860649).

21011021111 is a wasteful number, since it uses less digits than its factorization.

21011021111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12514105.

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

Adding to 21011021111 its reverse (11112011012), we get a palindrome (32123032123).

The spelling of 21011021111 in words is "twenty-one billion, eleven million, twenty-one thousand, one hundred eleven".