20985171 has 16 divisors (see below), whose sum is σ = 29503488. Its totient is φ = 13248000.

The previous prime is 20985169. The next prime is 20985187. The reversal of 20985171 is 17158902.

It is not a de Polignac number, because 20985171 - 2¹ = 20985169 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20985121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1971 + ... + 6771.

It is an arithmetic number, because the mean of its divisors is an integer number (1843968).

Almost surely, 2^20985171 is an apocalyptic number.

20985171 is a deficient number, since it is larger than the sum of its proper divisors (8518317).

20985171 is a wasteful number, since it uses less digits than its factorization.

20985171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4882.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 20985171 is about 4580.9574326771. The cubic root of 20985171 is about 275.8274625265.

The spelling of 20985171 in words is "twenty million, nine hundred eighty-five thousand, one hundred seventy-one".