31122122220 has 288 divisors, whose sum is σ = 109063438848. Its totient is φ = 7036793856.

The previous prime is 31122122203. The next prime is 31122122233. The reversal of 31122122220 is 2222122113.

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

It is a junction number, because it is equal to n+sod(n) for n = 31122122193 and 31122122202.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 66642427 + ... + 66642893.

It is an arithmetic number, because the mean of its divisors is an integer number (378692496).

Almost surely, 2^31122122220 is an apocalyptic number.

31122122220 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 31122122220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (54531719424).

31122122220 is an abundant number, since it is smaller than the sum of its proper divisors (77941316628).

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

31122122220 is a wasteful number, since it uses less digits than its factorization.

31122122220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 949 (or 944 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 31122122220 its reverse (2222122113), we get a palindrome (33344244333).

The spelling of 31122122220 in words is "thirty-one billion, one hundred twenty-two million, one hundred twenty-two thousand, two hundred twenty".