31218120 has 96 divisors (see below), whose sum is σ = 107448120. Its totient is φ = 7833600.

The previous prime is 31218119. The next prime is 31218133. The reversal of 31218120 is 2181213.

It can be written as a sum of positive squares in 4 ways, for example, as 18301284 + 12916836 = 4278^2 + 3594^2 .

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 = 31218093 and 31218102.

It is an unprimeable number.

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, 3570 + ... + 8670.

Almost surely, 2^31218120 is an apocalyptic number.

31218120 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 31218120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (53724060).

31218120 is an abundant number, since it is smaller than the sum of its proper divisors (76230000).

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

31218120 is a wasteful number, since it uses less digits than its factorization.

31218120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5135 (or 5128 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 31218120 is about 5587.3177822637. The cubic root of 31218120 is about 314.8731159417.

Adding to 31218120 its reverse (2181213), we get a palindrome (33399333).

The spelling of 31218120 in words is "thirty-one million, two hundred eighteen thousand, one hundred twenty".