31130320021 has 4 divisors (see below), whose sum is σ = 31162184172. Its totient is φ = 31098455872.

The previous prime is 31130320003. The next prime is 31130320027. The reversal of 31130320021 is 12002303113.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 24527944996 + 6602375025 = 156614^2 + 81255^2 .

It is a cyclic number.

It is not a de Polignac number, because 31130320021 - 2⁵ = 31130319989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31130319977 and 31130320004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31130320027) 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, 15930610 + ... + 15932563.

It is an arithmetic number, because the mean of its divisors is an integer number (7790546043).

Almost surely, 2^31130320021 is an apocalyptic number.

It is an amenable number.

31130320021 is a deficient number, since it is larger than the sum of its proper divisors (31864151).

31130320021 is an equidigital number, since it uses as much as digits as its factorization.

31130320021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31864150.

The product of its (nonzero) digits is 108, while the sum is 16.

Adding to 31130320021 its reverse (12002303113), we get a palindrome (43132623134).

The spelling of 31130320021 in words is "thirty-one billion, one hundred thirty million, three hundred twenty thousand, twenty-one".