21031320311 has 4 divisors (see below), whose sum is σ = 21038066400. Its totient is φ = 21024574224.

The previous prime is 21031320307. The next prime is 21031320397. The reversal of 21031320311 is 11302313012.

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 21031320311 - 2² = 21031320307 is a prime.

It is a super-2 number, since 2×21031320311² (a number of 21 digits) contains 22 as substring.

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 21031320311.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031323311) 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, 3368366 + ... + 3374603.

It is an arithmetic number, because the mean of its divisors is an integer number (5259516600).

Almost surely, 2^21031320311 is an apocalyptic number.

21031320311 is a deficient number, since it is larger than the sum of its proper divisors (6746089).

21031320311 is an equidigital number, since it uses as much as digits as its factorization.

21031320311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6746088.

The product of its (nonzero) digits is 108, while the sum is 17.

Adding to 21031320311 its reverse (11302313012), we get a palindrome (32333633323).

The spelling of 21031320311 in words is "twenty-one billion, thirty-one million, three hundred twenty thousand, three hundred eleven".