21001331311 has 4 divisors (see below), whose sum is σ = 21019578624. Its totient is φ = 20983084000.

The previous prime is 21001331243. The next prime is 21001331317. The reversal of 21001331311 is 11313310012.

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 21001331311 - 2¹⁵ = 21001298543 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001331317) 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, 9121930 + ... + 9124231.

It is an arithmetic number, because the mean of its divisors is an integer number (5254894656).

Almost surely, 2^21001331311 is an apocalyptic number.

21001331311 is a deficient number, since it is larger than the sum of its proper divisors (18247313).

21001331311 is a wasteful number, since it uses less digits than its factorization.

21001331311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18247312.

The product of its (nonzero) digits is 54, while the sum is 16.

Adding to 21001331311 its reverse (11313310012), we get a palindrome (32314641323).

The spelling of 21001331311 in words is "twenty-one billion, one million, three hundred thirty-one thousand, three hundred eleven".