18215805 has 16 divisors (see below), whose sum is σ = 29278080. Its totient is φ = 9670848.

The previous prime is 18215801. The next prime is 18215843. The reversal of 18215805 is 50851281.

It is not a de Polignac number, because 18215805 - 2² = 18215801 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18215801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 784 + ... + 6086.

It is an arithmetic number, because the mean of its divisors is an integer number (1829880).

Almost surely, 2^18215805 is an apocalyptic number.

18215805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18215805 is a deficient number, since it is larger than the sum of its proper divisors (11062275).

18215805 is a wasteful number, since it uses less digits than its factorization.

18215805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5540.

The product of its (nonzero) digits is 3200, while the sum is 30.

The square root of 18215805 is about 4267.9977741325. The cubic root of 18215805 is about 263.1173316392.

It can be divided in two parts, 1821 and 5805, that added together give a triangular number (7626 = T₁₂₃).

The spelling of 18215805 in words is "eighteen million, two hundred fifteen thousand, eight hundred five".