31145220 has 72 divisors (see below), whose sum is σ = 98594496. Its totient is φ = 7943232.

The previous prime is 31145167. The next prime is 31145221. The reversal of 31145220 is 2254113.

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 = 31145193 and 31145202.

It is not an unprimeable number, because it can be changed into a prime (31145221) 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 23 ways as a sum of consecutive naturals, for example, 379 + ... + 7901.

It is an arithmetic number, because the mean of its divisors is an integer number (1369368).

Almost surely, 2^31145220 is an apocalyptic number.

31145220 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 31145220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49297248).

31145220 is an abundant number, since it is smaller than the sum of its proper divisors (67449276).

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

31145220 is a wasteful number, since it uses less digits than its factorization.

31145220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7561 (or 7556 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 31145220 is about 5580.7902666200. The cubic root of 31145220 is about 314.6278295416.

Adding to 31145220 its reverse (2254113), we get a palindrome (33399333).

The spelling of 31145220 in words is "thirty-one million, one hundred forty-five thousand, two hundred twenty".