1218820 has 24 divisors (see below), whose sum is σ = 2583000. Its totient is φ = 483072.

The previous prime is 1218787. The next prime is 1218821. The reversal of 1218820 is 288121.

It can be written as a sum of positive squares in 4 ways, for example, as 141376 + 1077444 = 376^2 + 1038^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1218791 and 1218800.

It is not an unprimeable number, because it can be changed into a prime (1218821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2776 + ... + 3184.

It is an arithmetic number, because the mean of its divisors is an integer number (107625).

2^1218820 is an apocalyptic number.

1218820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1218820 is an abundant number, since it is smaller than the sum of its proper divisors (1364180).

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

1218820 is a wasteful number, since it uses less digits than its factorization.

1218820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 567 (or 565 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 1218820 is about 1104.0018115927. The cubic root of 1218820 is about 106.8185120365.

The spelling of 1218820 in words is "one million, two hundred eighteen thousand, eight hundred twenty".