31000021312 has 112 divisors (see below), whose sum is σ = 67028039680. Its totient is φ = 14140127232.

The previous prime is 31000021309. The next prime is 31000021319. The reversal of 31000021312 is 21312000013.

It is a super-2 number, since 2×31000021312² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a junction number, because it is equal to n+sod(n) for n = 31000021292 and 31000021301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31000021319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41948239 + ... + 41948977.

It is an arithmetic number, because the mean of its divisors is an integer number (598464640).

Almost surely, 2^31000021312 is an apocalyptic number.

31000021312 is a gapful number since it is divisible by the number (32) 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 31000021312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33514019840).

31000021312 is an abundant number, since it is smaller than the sum of its proper divisors (36028018368).

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

31000021312 is a wasteful number, since it uses less digits than its factorization.

31000021312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1288 (or 1278 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 13.

Adding to 31000021312 its reverse (21312000013), we get a palindrome (52312021325).

The spelling of 31000021312 in words is "thirty-one billion, twenty-one thousand, three hundred twelve".