1825821 has 10 divisors (see below), whose sum is σ = 2727582. Its totient is φ = 1217160.

The previous prime is 1825819. The next prime is 1825829. The reversal of 1825821 is 1285281.

1825821 is a `hidden beast` number, since 1 + 82 + 582 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1726596 + 99225 = 1314^2 + 315^2 .

It is not a de Polignac number, because 1825821 - 2¹ = 1825819 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1825829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 11190 + ... + 11351.

2^1825821 is an apocalyptic number.

It is an amenable number.

1825821 is a deficient number, since it is larger than the sum of its proper divisors (901761).

1825821 is an equidigital number, since it uses as much as digits as its factorization.

1825821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22553 (or 22544 counting only the distinct ones).

The product of its digits is 1280, while the sum is 27.

The square root of 1825821 is about 1351.2294401766. The cubic root of 1825821 is about 122.2229418078. Note that the first 3 decimals are identical.

The spelling of 1825821 in words is "one million, eight hundred twenty-five thousand, eight hundred twenty-one".