20381818 has 16 divisors (see below), whose sum is σ = 32933376. Its totient is φ = 9432720.

The previous prime is 20381807. The next prime is 20381821. The reversal of 20381818 is 81818302.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a self number, because there is not a number n which added to its sum of digits gives 20381818.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 5721 + ... + 8572.

It is an arithmetic number, because the mean of its divisors is an integer number (2058336).

Almost surely, 2^20381818 is an apocalyptic number.

20381818 is a deficient number, since it is larger than the sum of its proper divisors (12551558).

20381818 is a wasteful number, since it uses less digits than its factorization.

20381818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14349.

The product of its (nonzero) digits is 3072, while the sum is 31.

The square root of 20381818 is about 4514.6226863383. The cubic root of 20381818 is about 273.1582403640.

The spelling of 20381818 in words is "twenty million, three hundred eighty-one thousand, eight hundred eighteen".