20665231 has 4 divisors (see below), whose sum is σ = 20858472. Its totient is φ = 20471992.

The previous prime is 20665213. The next prime is 20665237. The reversal of 20665231 is 13256602.

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 20665231 - 2¹¹ = 20663183 is a prime.

It is a super-2 number, since 2×20665231² = 854103544566722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20665196 and 20665205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20665237) 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, 96460 + ... + 96673.

It is an arithmetic number, because the mean of its divisors is an integer number (5214618).

Almost surely, 2^20665231 is an apocalyptic number.

20665231 is a deficient number, since it is larger than the sum of its proper divisors (193241).

20665231 is a wasteful number, since it uses less digits than its factorization.

20665231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193240.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 20665231 is about 4545.9026606385. The cubic root of 20665231 is about 274.4185223170.

The spelling of 20665231 in words is "twenty million, six hundred sixty-five thousand, two hundred thirty-one".