31138943220 has 576 divisors, whose sum is σ = 123978097152. Its totient is φ = 6137856000.

The previous prime is 31138943191. The next prime is 31138943221. The reversal of 31138943220 is 2234983113.

31138943220 is a `hidden beast` number, since 3 + 11 + 389 + 43 + 220 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31138943221) 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 191 ways as a sum of consecutive naturals, for example, 21024880 + ... + 21026360.

It is an arithmetic number, because the mean of its divisors is an integer number (215239752).

Almost surely, 2^31138943220 is an apocalyptic number.

31138943220 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 31138943220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (61989048576).

31138943220 is an abundant number, since it is smaller than the sum of its proper divisors (92839153932).

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

31138943220 is a wasteful number, since it uses less digits than its factorization.

31138943220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1592 (or 1587 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The spelling of 31138943220 in words is "thirty-one billion, one hundred thirty-eight million, nine hundred forty-three thousand, two hundred twenty".