20685493 has 4 divisors (see below), whose sum is σ = 20836620. Its totient is φ = 20534368.

The previous prime is 20685473. The next prime is 20685503. The reversal of 20685493 is 39458602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 39458602 = 2 ⋅19729301.

It can be written as a sum of positive squares in 2 ways, for example, as 10712529 + 9972964 = 3273^2 + 3158^2 .

It is a cyclic number.

It is not a de Polignac number, because 20685493 - 2¹⁷ = 20554421 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 (20685403) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75358 + ... + 75631.

It is an arithmetic number, because the mean of its divisors is an integer number (5209155).

Almost surely, 2^20685493 is an apocalyptic number.

It is an amenable number.

20685493 is a deficient number, since it is larger than the sum of its proper divisors (151127).

20685493 is a wasteful number, since it uses less digits than its factorization.

20685493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151126.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 20685493 is about 4548.1307149201. The cubic root of 20685493 is about 274.5081809942.

The spelling of 20685493 in words is "twenty million, six hundred eighty-five thousand, four hundred ninety-three".