31121302440 has 128 divisors (see below), whose sum is σ = 96765840000. Its totient is φ = 7997703168.

The previous prime is 31121302439. The next prime is 31121302441. The reversal of 31121302440 is 4420312113.

It is an interprime number because it is at equal distance from previous prime (31121302439) and next prime (31121302441).

It is not an unprimeable number, because it can be changed into a prime (31121302441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1895386 + ... + 1911734.

It is an arithmetic number, because the mean of its divisors is an integer number (755983125).

Almost surely, 2^31121302440 is an apocalyptic number.

31121302440 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31121302440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48382920000).

31121302440 is an abundant number, since it is smaller than the sum of its proper divisors (65644537560).

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

31121302440 is a wasteful number, since it uses less digits than its factorization.

31121302440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16939 (or 16935 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

Adding to 31121302440 its reverse (4420312113), we get a palindrome (35541614553).

The spelling of 31121302440 in words is "thirty-one billion, one hundred twenty-one million, three hundred two thousand, four hundred forty".