1645220 has 12 divisors (see below), whose sum is σ = 3455004. Its totient is φ = 658080.

The previous prime is 1645211. The next prime is 1645249. The reversal of 1645220 is 225461.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 341056 + 1304164 = 584^2 + 1142^2 .

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: 82261 = 1645220 / (1 + 6 + 4 + 5 + 2 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 1645192 and 1645201.

It is a congruent number.

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, 41111 + ... + 41150.

It is an arithmetic number, because the mean of its divisors is an integer number (287917).

2^1645220 is an apocalyptic number.

1645220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1645220 is an abundant number, since it is smaller than the sum of its proper divisors (1809784).

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

1645220 is a wasteful number, since it uses less digits than its factorization.

1645220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82270 (or 82268 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 1645220 is about 1282.6612959001. The cubic root of 1645220 is about 118.0523563506.

The spelling of 1645220 in words is "one million, six hundred forty-five thousand, two hundred twenty".