31121680 has 80 divisors (see below), whose sum is σ = 75620160. Its totient is φ = 11902464.

The previous prime is 31121663. The next prime is 31121687. The reversal of 31121680 is 8612113.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (31121687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 285466 + ... + 285574.

It is an arithmetic number, because the mean of its divisors is an integer number (945252).

Almost surely, 2^31121680 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 31121680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37810080).

31121680 is an abundant number, since it is smaller than the sum of its proper divisors (44498480).

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

31121680 is a wasteful number, since it uses less digits than its factorization.

31121680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248 (or 242 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 31121680 is about 5578.6808476557. The cubic root of 31121680 is about 314.5485428343.

Adding to 31121680 its reverse (8612113), we get a palindrome (39733793).

The spelling of 31121680 in words is "thirty-one million, one hundred twenty-one thousand, six hundred eighty".