21011121211 has 8 divisors (see below), whose sum is σ = 21577279248. Its totient is φ = 20447520000.

The previous prime is 21011121179. The next prime is 21011121227. The reversal of 21011121211 is 11212111012.

It is a happy number.

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

It is not a de Polignac number, because 21011121211 - 2⁵ = 21011121179 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011121191 and 21011121200.

It is not an unprimeable number, because it can be changed into a prime (21011121281) 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, 622545 + ... + 655426.

It is an arithmetic number, because the mean of its divisors is an integer number (2697159906).

Almost surely, 2^21011121211 is an apocalyptic number.

21011121211 is a deficient number, since it is larger than the sum of its proper divisors (566158037).

21011121211 is a wasteful number, since it uses less digits than its factorization.

21011121211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1278413.

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

Adding to 21011121211 its reverse (11212111012), we get a palindrome (32223232223).

The spelling of 21011121211 in words is "twenty-one billion, eleven million, one hundred twenty-one thousand, two hundred eleven".