20684191 has 4 divisors (see below), whose sum is σ = 22564584. Its totient is φ = 18803800.

The previous prime is 20684171. The next prime is 20684197. The reversal of 20684191 is 19148602.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20684191 - 2⁵ = 20684159 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20684197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 940180 + ... + 940201.

It is an arithmetic number, because the mean of its divisors is an integer number (5641146).

Almost surely, 2^20684191 is an apocalyptic number.

20684191 is a deficient number, since it is larger than the sum of its proper divisors (1880393).

20684191 is a wasteful number, since it uses less digits than its factorization.

20684191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1880392.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 20684191 is about 4547.9875769399. The cubic root of 20684191 is about 274.5024214482.

The spelling of 20684191 in words is "twenty million, six hundred eighty-four thousand, one hundred ninety-one".