12661220 has 96 divisors (see below), whose sum is σ = 33022080. Its totient is φ = 4008960.

The previous prime is 12661213. The next prime is 12661241. The reversal of 12661220 is 2216621.

12661220 = T₁₄₄ + T₁₄₅ + ... + T₄₂₈.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 12661192 and 12661201.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 54224 + ... + 54456.

It is an arithmetic number, because the mean of its divisors is an integer number (343980).

Almost surely, 2^12661220 is an apocalyptic number.

12661220 is a gapful number since it is divisible by the number (10) 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 12661220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16511040).

12661220 is an abundant number, since it is smaller than the sum of its proper divisors (20360860).

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

12661220 is a wasteful number, since it uses less digits than its factorization.

12661220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285 (or 283 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 12661220 is about 3558.2608111267. The cubic root of 12661220 is about 233.0729385383.

Adding to 12661220 its reverse (2216621), we get a palindrome (14877841).

The spelling of 12661220 in words is "twelve million, six hundred sixty-one thousand, two hundred twenty".