21011221111 has 8 divisors (see below), whose sum is σ = 22383663984. Its totient is φ = 19653943680.

The previous prime is 21011221097. The next prime is 21011221129. The reversal of 21011221111 is 11112211012.

It is a happy number.

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 21011221111 - 2⁷ = 21011220983 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011221091 and 21011221100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011221141) 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, 3788500 + ... + 3794041.

It is an arithmetic number, because the mean of its divisors is an integer number (2797957998).

Almost surely, 2^21011221111 is an apocalyptic number.

21011221111 is a deficient number, since it is larger than the sum of its proper divisors (1372442873).

21011221111 is a wasteful number, since it uses less digits than its factorization.

21011221111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7582721.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21011221111 its reverse (11112211012), we get a palindrome (32123432123).

The spelling of 21011221111 in words is "twenty-one billion, eleven million, two hundred twenty-one thousand, one hundred eleven".