20001855 has 8 divisors (see below), whose sum is σ = 32002992. Its totient is φ = 10667648.

The previous prime is 20001853. The next prime is 20001899. The reversal of 20001855 is 55810002.

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

It is a cyclic number.

It is not a de Polignac number, because 20001855 - 2¹ = 20001853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20001853) by changing a digit.

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, 666714 + ... + 666743.

It is an arithmetic number, because the mean of its divisors is an integer number (4000374).

Almost surely, 2^20001855 is an apocalyptic number.

20001855 is a deficient number, since it is larger than the sum of its proper divisors (12001137).

20001855 is a wasteful number, since it uses less digits than its factorization.

20001855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333465.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 20001855 is about 4472.3433454957. The cubic root of 20001855 is about 271.4501534745.

Adding to 20001855 its reverse (55810002), we get a palindrome (75811857).

The spelling of 20001855 in words is "twenty million, one thousand, eight hundred fifty-five".