21001231311 has 4 divisors (see below), whose sum is σ = 28001641752. Its totient is φ = 14000820872.

The previous prime is 21001231301. The next prime is 21001231327. The reversal of 21001231311 is 11313210012.

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 21001231311 - 2⁹ = 21001230799 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001231301) 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, 3500205216 + ... + 3500205221.

It is an arithmetic number, because the mean of its divisors is an integer number (7000410438).

Almost surely, 2^21001231311 is an apocalyptic number.

21001231311 is a deficient number, since it is larger than the sum of its proper divisors (7000410441).

21001231311 is an equidigital number, since it uses as much as digits as its factorization.

21001231311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7000410440.

The product of its (nonzero) digits is 36, while the sum is 15.

Adding to 21001231311 its reverse (11313210012), we get a palindrome (32314441323).

The spelling of 21001231311 in words is "twenty-one billion, one million, two hundred thirty-one thousand, three hundred eleven".