21031031311 has 4 divisors (see below), whose sum is σ = 21033815992. Its totient is φ = 21028246632.

The previous prime is 21031031309. The next prime is 21031031317. The reversal of 21031031311 is 11313013012.

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 21031031311 - 2¹ = 21031031309 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 (21031031317) 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, 1380981 + ... + 1396126.

It is an arithmetic number, because the mean of its divisors is an integer number (5258453998).

Almost surely, 2^21031031311 is an apocalyptic number.

21031031311 is a deficient number, since it is larger than the sum of its proper divisors (2784681).

21031031311 is an equidigital number, since it uses as much as digits as its factorization.

21031031311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2784680.

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

Adding to 21031031311 its reverse (11313013012), we get a palindrome (32344044323).

The spelling of 21031031311 in words is "twenty-one billion, thirty-one million, thirty-one thousand, three hundred eleven".