31131023220 has 240 divisors, whose sum is σ = 112805275968. Its totient is φ = 7102909440.

The previous prime is 31131023219. The next prime is 31131023243. The reversal of 31131023220 is 2232013113.

31131023220 is a `hidden beast` number, since 31 + 1 + 310 + 2 + 322 + 0 = 666.

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 = 31131023193 and 31131023202.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 251559 + ... + 354321.

Almost surely, 2^31131023220 is an apocalyptic number.

31131023220 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 31131023220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56402637984).

31131023220 is an abundant number, since it is smaller than the sum of its proper divisors (81674252748).

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

31131023220 is a wasteful number, since it uses less digits than its factorization.

31131023220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102812 (or 102801 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

Adding to 31131023220 its reverse (2232013113), we get a palindrome (33363036333).

The spelling of 31131023220 in words is "thirty-one billion, one hundred thirty-one million, twenty-three thousand, two hundred twenty".