18825821 has 4 divisors (see below), whose sum is σ = 21515232. Its totient is φ = 16136412.

The previous prime is 18825809. The next prime is 18825823. The reversal of 18825821 is 12852881.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18825821 - 2⁶ = 18825757 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18825823) 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 3 ways as a sum of consecutive naturals, for example, 1344695 + ... + 1344708.

It is an arithmetic number, because the mean of its divisors is an integer number (5378808).

Almost surely, 2^18825821 is an apocalyptic number.

It is an amenable number.

18825821 is a deficient number, since it is larger than the sum of its proper divisors (2689411).

18825821 is an equidigital number, since it uses as much as digits as its factorization.

18825821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2689410.

The product of its digits is 10240, while the sum is 35.

The square root of 18825821 is about 4338.8732408311. The cubic root of 18825821 is about 266.0222577339.

The spelling of 18825821 in words is "eighteen million, eight hundred twenty-five thousand, eight hundred twenty-one".