20685121 has 4 divisors (see below), whose sum is σ = 20809152. Its totient is φ = 20561092.

The previous prime is 20685101. The next prime is 20685131. The reversal of 20685121 is 12158602.

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 20685121 - 2⁵ = 20685089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20685101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61765 + ... + 62098.

It is an arithmetic number, because the mean of its divisors is an integer number (5202288).

Almost surely, 2^20685121 is an apocalyptic number.

It is an amenable number.

20685121 is a deficient number, since it is larger than the sum of its proper divisors (124031).

20685121 is a wasteful number, since it uses less digits than its factorization.

20685121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124030.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 20685121 is about 4548.0898188140. The cubic root of 20685121 is about 274.5065354343.

The spelling of 20685121 in words is "twenty million, six hundred eighty-five thousand, one hundred twenty-one".