21231020011 has 4 divisors (see below), whose sum is σ = 21256326000. Its totient is φ = 21205714024.

The previous prime is 21231020009. The next prime is 21231020017. The reversal of 21231020011 is 11002013212.

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 21231020011 - 2¹ = 21231020009 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21231019973 and 21231020000.

It is not an unprimeable number, because it can be changed into a prime (21231020017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12651736 + ... + 12653413.

It is an arithmetic number, because the mean of its divisors is an integer number (5314081500).

Almost surely, 2^21231020011 is an apocalyptic number.

21231020011 is a deficient number, since it is larger than the sum of its proper divisors (25305989).

21231020011 is an equidigital number, since it uses as much as digits as its factorization.

21231020011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25305988.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21231020011 its reverse (11002013212), we get a palindrome (32233033223).

The spelling of 21231020011 in words is "twenty-one billion, two hundred thirty-one million, twenty thousand, eleven".