20172081 has 32 divisors (see below), whose sum is σ = 30792960. Its totient is φ = 11669504.

The previous prime is 20172079. The next prime is 20172101. The reversal of 20172081 is 18027102.

It is a cyclic number.

It is not a de Polignac number, because 20172081 - 2¹ = 20172079 is a prime.

It is a super-2 number, since 2×20172081² = 813825703741122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20172001) 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 31 ways as a sum of consecutive naturals, for example, 33721 + ... + 34313.

It is an arithmetic number, because the mean of its divisors is an integer number (962280).

Almost surely, 2^20172081 is an apocalyptic number.

It is an amenable number.

20172081 is a deficient number, since it is larger than the sum of its proper divisors (10620879).

20172081 is a wasteful number, since it uses less digits than its factorization.

20172081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 665.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 20172081 is about 4491.3339889169. Note that the first 3 decimals coincide. The cubic root of 20172081 is about 272.2180390182.

Adding to 20172081 its reverse (18027102), we get a palindrome (38199183).

The spelling of 20172081 in words is "twenty million, one hundred seventy-two thousand, eighty-one".