31123216 has 40 divisors (see below), whose sum is σ = 65214080. Its totient is φ = 14338944.

The previous prime is 31123199. The next prime is 31123217. The reversal of 31123216 is 61232113.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a junction number, because it is equal to n+sod(n) for n = 31123193 and 31123202.

It is not an unprimeable number, because it can be changed into a prime (31123217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9865 + ... + 12631.

It is an arithmetic number, because the mean of its divisors is an integer number (1630352).

Almost surely, 2^31123216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31123216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32607040).

31123216 is an abundant number, since it is smaller than the sum of its proper divisors (34090864).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31123216 is a wasteful number, since it uses less digits than its factorization.

31123216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2831 (or 2825 counting only the distinct ones).

The product of its digits is 216, while the sum is 19.

The square root of 31123216 is about 5578.8185129111. The cubic root of 31123216 is about 314.5537175615.

Adding to 31123216 its reverse (61232113), we get a palindrome (92355329).

It can be divided in two parts, 3112 and 3216, that added together give a triangular number (6328 = T₁₁₂).

The spelling of 31123216 in words is "thirty-one million, one hundred twenty-three thousand, two hundred sixteen".