18215825 has 12 divisors (see below), whose sum is σ = 22676748. Its totient is φ = 14515200.

The previous prime is 18215801. The next prime is 18215843. The reversal of 18215825 is 52851281.

It is a happy number.

It is a Cunningham number, because it is equal to 4268²+1.

It can be written as a sum of positive squares in 6 ways, for example, as 1 + 18215824 = 1^2 + 4268^2 .

It is not a de Polignac number, because 18215825 - 2¹² = 18211729 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 18215791 and 18215800.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 5729 + ... + 8321.

It is an arithmetic number, because the mean of its divisors is an integer number (1889729).

Almost surely, 2^18215825 is an apocalyptic number.

It is an amenable number.

18215825 is a deficient number, since it is larger than the sum of its proper divisors (4460923).

18215825 is a wasteful number, since it uses less digits than its factorization.

18215825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2884 (or 2879 counting only the distinct ones).

The product of its digits is 6400, while the sum is 32.

The square root of 18215825 is about 4268.0001171509. Note that the first 3 decimals coincide. The cubic root of 18215825 is about 263.1174279355.

The spelling of 18215825 in words is "eighteen million, two hundred fifteen thousand, eight hundred twenty-five".