20684591 has 8 divisors (see below), whose sum is σ = 21739344. Its totient is φ = 19656000.

The previous prime is 20684581. The next prime is 20684611. The reversal of 20684591 is 19548602.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20684591 - 2¹⁸ = 20422447 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 (20684561) 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 7 ways as a sum of consecutive naturals, for example, 4910 + ... + 8091.

It is an arithmetic number, because the mean of its divisors is an integer number (2717418).

Almost surely, 2^20684591 is an apocalyptic number.

20684591 is a deficient number, since it is larger than the sum of its proper divisors (1054753).

20684591 is a wasteful number, since it uses less digits than its factorization.

20684591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13081.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 20684591 is about 4548.0315522212. The cubic root of 20684591 is about 274.5041909197.

The spelling of 20684591 in words is "twenty million, six hundred eighty-four thousand, five hundred ninety-one".