12731220 has 36 divisors (see below), whose sum is σ = 38618580. Its totient is φ = 3394944.

The previous prime is 12731189. The next prime is 12731227. The reversal of 12731220 is 2213721.

It can be written as a sum of positive squares in 2 ways, for example, as 6320196 + 6411024 = 2514^2 + 2532^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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 = 12731193 and 12731202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12731227) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 35185 + ... + 35544.

Almost surely, 2^12731220 is an apocalyptic number.

12731220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

12731220 is an abundant number, since it is smaller than the sum of its proper divisors (25887360).

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

12731220 is a wasteful number, since it uses less digits than its factorization.

12731220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70744 (or 70739 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 12731220 is about 3568.0835192019. The cubic root of 12731220 is about 233.5016789661.

Adding to 12731220 its reverse (2213721), we get a palindrome (14944941).

The spelling of 12731220 in words is "twelve million, seven hundred thirty-one thousand, two hundred twenty".