20857231 has 8 divisors (see below), whose sum is σ = 22183280. Its totient is φ = 19554048.

The previous prime is 20857217. The next prime is 20857247. The reversal of 20857231 is 13275802.

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 20857231 - 2⁷ = 20857103 is a prime.

It is a super-2 number, since 2×20857231² = 870048169974722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20857231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20857211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3816 + ... + 7501.

It is an arithmetic number, because the mean of its divisors is an integer number (2772910).

Almost surely, 2^20857231 is an apocalyptic number.

20857231 is a deficient number, since it is larger than the sum of its proper divisors (1326049).

20857231 is a wasteful number, since it uses less digits than its factorization.

20857231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11433.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 20857231 is about 4566.9717537992. The cubic root of 20857231 is about 275.2657750137.

It can be divided in two parts, 2085 and 7231, that added together give a triangular number (9316 = T₁₃₆).

The spelling of 20857231 in words is "twenty million, eight hundred fifty-seven thousand, two hundred thirty-one".