1681220 has 12 divisors (see below), whose sum is σ = 3530604. Its totient is φ = 672480.

The previous prime is 1681219. The next prime is 1681241. The reversal of 1681220 is 221861.

It can be written as a sum of positive squares in 2 ways, for example, as 246016 + 1435204 = 496^2 + 1198^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 84061 = 1681220 / (1 + 6 + 8 + 1 + 2 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 1681192 and 1681201.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42011 + ... + 42050.

It is an arithmetic number, because the mean of its divisors is an integer number (294217).

2^1681220 is an apocalyptic number.

1681220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1681220 is an abundant number, since it is smaller than the sum of its proper divisors (1849384).

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

1681220 is a wasteful number, since it uses less digits than its factorization.

1681220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84070 (or 84068 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 1681220 is about 1296.6186794891. The cubic root of 1681220 is about 118.9072082225.

The spelling of 1681220 in words is "one million, six hundred eighty-one thousand, two hundred twenty".