31120021020 has 192 divisors, whose sum is σ = 96902023680. Its totient is φ = 7399296000.

The previous prime is 31120020937. The next prime is 31120021021. The reversal of 31120021020 is 2012002113.

31120021020 = 499² + 500² + ... + 4538².

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 31120020987 and 31120021005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31120021021) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 7263799 + ... + 7268081.

It is an arithmetic number, because the mean of its divisors is an integer number (504698040).

Almost surely, 2^31120021020 is an apocalyptic number.

31120021020 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 31120021020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48451011840).

31120021020 is an abundant number, since it is smaller than the sum of its proper divisors (65782002660).

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

31120021020 is a wasteful number, since it uses less digits than its factorization.

31120021020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4516 (or 4514 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 31120021020 its reverse (2012002113), we get a palindrome (33132023133).

The spelling of 31120021020 in words is "thirty-one billion, one hundred twenty million, twenty-one thousand, twenty".