21010101011 has 4 divisors (see below), whose sum is σ = 21118961832. Its totient is φ = 20901240192.

The previous prime is 21010100971. The next prime is 21010101041. The reversal of 21010101011 is 11010101012.

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 21010101011 - 2¹⁰ = 21010099987 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21010101011.

It is not an unprimeable number, because it can be changed into a prime (21010101041) 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, 54430121 + ... + 54430506.

It is an arithmetic number, because the mean of its divisors is an integer number (5279740458).

Almost surely, 2^21010101011 is an apocalyptic number.

21010101011 is a deficient number, since it is larger than the sum of its proper divisors (108860821).

21010101011 is a wasteful number, since it uses less digits than its factorization.

21010101011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108860820.

The product of its (nonzero) digits is 2, while the sum is 8.

Adding to 21010101011 its reverse (11010101012), we get a palindrome (32020202023).

Subtracting from 21010101011 its reverse (11010101012), we obtain a palindrome (9999999999).

The spelling of 21010101011 in words is "twenty-one billion, ten million, one hundred one thousand, eleven".