20531985 has 16 divisors (see below), whose sum is σ = 34280064. Its totient is φ = 10474112.

The previous prime is 20531983. The next prime is 20531999. The reversal of 20531985 is 58913502.

It is a cyclic number.

It is not a de Polignac number, because 20531985 - 2¹ = 20531983 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20531981) 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 15 ways as a sum of consecutive naturals, for example, 29412 + ... + 30101.

It is an arithmetic number, because the mean of its divisors is an integer number (2142504).

It is the magic constant of a 345 × 345 magic square.

Almost surely, 2^20531985 is an apocalyptic number.

It is an amenable number.

20531985 is a deficient number, since it is larger than the sum of its proper divisors (13748079).

20531985 is a wasteful number, since it uses less digits than its factorization.

20531985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59544.

The product of its (nonzero) digits is 10800, while the sum is 33.

The square root of 20531985 is about 4531.2233447492. The cubic root of 20531985 is about 273.8274483228.

The spelling of 20531985 in words is "twenty million, five hundred thirty-one thousand, nine hundred eighty-five".