1815818 has 4 divisors (see below), whose sum is σ = 2723730. Its totient is φ = 907908.

The previous prime is 1815817. The next prime is 1815823. The reversal of 1815818 is 8185181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8185181 = 19 ⋅430799.

It can be written as a sum of positive squares in only one way, i.e., 1138489 + 677329 = 1067^2 + 823^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1815817) by changing a digit.

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 as a sum of consecutive naturals, namely, 453953 + ... + 453956.

2^1815818 is an apocalyptic number.

1815818 is a deficient number, since it is larger than the sum of its proper divisors (907912).

1815818 is an equidigital number, since it uses as much as digits as its factorization.

1815818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 907911.

The product of its digits is 2560, while the sum is 32.

The square root of 1815818 is about 1347.5229126067. The cubic root of 1815818 is about 121.9993281339. Note that the first 3 decimals are identical.

The spelling of 1815818 in words is "one million, eight hundred fifteen thousand, eight hundred eighteen".