31220113212 has 72 divisors (see below), whose sum is σ = 81682932240. Its totient is φ = 10042421760.

The previous prime is 31220113187. The next prime is 31220113229. The reversal of 31220113212 is 21231102213.

31220113212 is a `hidden beast` number, since 312 + 20 + 11 + 321 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2217748 + ... + 2231780.

It is an arithmetic number, because the mean of its divisors is an integer number (1134485170).

Almost surely, 2^31220113212 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 31220113212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40841466120).

31220113212 is an abundant number, since it is smaller than the sum of its proper divisors (50462819028).

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

31220113212 is a wasteful number, since it uses less digits than its factorization.

31220113212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16203 (or 16198 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 31220113212 its reverse (21231102213), we get a palindrome (52451215425).

The spelling of 31220113212 in words is "thirty-one billion, two hundred twenty million, one hundred thirteen thousand, two hundred twelve".