1821225 has 24 divisors (see below), whose sum is σ = 3442240. Its totient is φ = 832320.

The previous prime is 1821191. The next prime is 1821233. The reversal of 1821225 is 5221281.

It is a happy number.

It is not a de Polignac number, because 1821225 - 2⁸ = 1820969 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

1821225 is a lucky number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1210 + ... + 2259.

2^1821225 is an apocalyptic number.

1821225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1821225 is a deficient number, since it is larger than the sum of its proper divisors (1621015).

1821225 is a wasteful number, since it uses less digits than its factorization.

1821225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3489 (or 3484 counting only the distinct ones).

The product of its digits is 320, while the sum is 21.

The square root of 1821225 is about 1349.5276951586. The cubic root of 1821225 is about 122.1203014724.

The spelling of 1821225 in words is "one million, eight hundred twenty-one thousand, two hundred twenty-five".