20381985 has 24 divisors (see below), whose sum is σ = 38047464. Its totient is φ = 10033920.

The previous prime is 20381981. The next prime is 20381993. The reversal of 20381985 is 58918302.

It can be written as a sum of positive squares in 4 ways, for example, as 104976 + 20277009 = 324^2 + 4503^2 .

It is not a de Polignac number, because 20381985 - 2² = 20381981 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20381981) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16836 + ... + 18005.

It is an arithmetic number, because the mean of its divisors is an integer number (1585311).

Almost surely, 2^20381985 is an apocalyptic number.

It is an amenable number.

20381985 is a deficient number, since it is larger than the sum of its proper divisors (17665479).

20381985 is a wasteful number, since it uses less digits than its factorization.

20381985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34865 (or 34862 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 20381985 is about 4514.6411817552. The cubic root of 20381985 is about 273.1589864097.

The spelling of 20381985 in words is "twenty million, three hundred eighty-one thousand, nine hundred eighty-five".