20381805 has 18 divisors (see below), whose sum is σ = 35381034. Its totient is φ = 10854144.

The previous prime is 20381791. The next prime is 20381807. The reversal of 20381805 is 50818302.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 427716 + 19954089 = 654^2 + 4467^2 .

It is not a de Polignac number, because 20381805 - 2⁴ = 20381789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20381807) 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 in 17 ways as a sum of consecutive naturals, for example, 29949 + ... + 30621.

It is an arithmetic number, because the mean of its divisors is an integer number (1965613).

Almost surely, 2^20381805 is an apocalyptic number.

It is an amenable number.

20381805 is a deficient number, since it is larger than the sum of its proper divisors (14999229).

20381805 is an frugal number, since it uses more digits than its factorization.

20381805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1357 (or 681 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 20381805 is about 4514.6212465721. The cubic root of 20381805 is about 273.1581822884.

The spelling of 20381805 in words is "twenty million, three hundred eighty-one thousand, eight hundred five".