20081815 has 8 divisors (see below), whose sum is σ = 25951968. Its totient is φ = 14829600.

The previous prime is 20081797. The next prime is 20081821. The reversal of 20081815 is 51818002.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20081815 - 2¹¹ = 20079767 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20081815.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 154411 + ... + 154540.

It is an arithmetic number, because the mean of its divisors is an integer number (3243996).

Almost surely, 2^20081815 is an apocalyptic number.

20081815 is a deficient number, since it is larger than the sum of its proper divisors (5870153).

20081815 is a wasteful number, since it uses less digits than its factorization.

20081815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308969.

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 20081815 is about 4481.2738144416. The cubic root of 20081815 is about 271.8113915577.

Adding to 20081815 its reverse (51818002), we get a palindrome (71899817).

The spelling of 20081815 in words is "twenty million, eighty-one thousand, eight hundred fifteen".