20671685 has 4 divisors (see below), whose sum is σ = 24806028. Its totient is φ = 16537344.

The previous prime is 20671661. The next prime is 20671723. The reversal of 20671685 is 58617602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58617602 = 2 ⋅29308801.

It can be written as a sum of positive squares in 2 ways, for example, as 3771364 + 16900321 = 1942^2 + 4111^2 .

It is a cyclic number.

It is not a de Polignac number, because 20671685 - 2⁶ = 20671621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2067164 + ... + 2067173.

It is an arithmetic number, because the mean of its divisors is an integer number (6201507).

Almost surely, 2^20671685 is an apocalyptic number.

It is an amenable number.

20671685 is a deficient number, since it is larger than the sum of its proper divisors (4134343).

20671685 is an equidigital number, since it uses as much as digits as its factorization.

20671685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4134342.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 20671685 is about 4546.6124752391. The cubic root of 20671685 is about 274.4470874109.

The spelling of 20671685 in words is "twenty million, six hundred seventy-one thousand, six hundred eighty-five".