20170861 has 4 divisors (see below), whose sum is σ = 20512800. Its totient is φ = 19828924.

The previous prime is 20170853. The next prime is 20170867. The reversal of 20170861 is 16807102.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20170861 - 2³ = 20170853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20170867) 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 3 ways as a sum of consecutive naturals, for example, 170881 + ... + 170998.

It is an arithmetic number, because the mean of its divisors is an integer number (5128200).

Almost surely, 2^20170861 is an apocalyptic number.

It is an amenable number.

20170861 is a deficient number, since it is larger than the sum of its proper divisors (341939).

20170861 is an equidigital number, since it uses as much as digits as its factorization.

20170861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341938.

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 20170861 is about 4491.1981697538. The cubic root of 20170861 is about 272.2125510254.

Adding to 20170861 its reverse (16807102), we get a palindrome (36977963).

The spelling of 20170861 in words is "twenty million, one hundred seventy thousand, eight hundred sixty-one".