31311320321 has 4 divisors (see below), whose sum is σ = 32321362944. Its totient is φ = 30301277700.

The previous prime is 31311320297. The next prime is 31311320323. The reversal of 31311320321 is 12302311313.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12302311313 = 89 ⋅138228217.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31311320321 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 31311320293 and 31311320302.

It is not an unprimeable number, because it can be changed into a prime (31311320323) 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, 505021265 + ... + 505021326.

It is an arithmetic number, because the mean of its divisors is an integer number (8080340736).

Almost surely, 2^31311320321 is an apocalyptic number.

31311320321 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

31311320321 is a deficient number, since it is larger than the sum of its proper divisors (1010042623).

31311320321 is a wasteful number, since it uses less digits than its factorization.

31311320321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1010042622.

The product of its (nonzero) digits is 324, while the sum is 20.

Adding to 31311320321 its reverse (12302311313), we get a palindrome (43613631634).

The spelling of 31311320321 in words is "thirty-one billion, three hundred eleven million, three hundred twenty thousand, three hundred twenty-one".