20357 has 2 divisors, whose sum is σ = 20358. Its totient is φ = 20356.

The previous prime is 20353. The next prime is 20359. The reversal of 20357 is 75302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17956 + 2401 = 134^2 + 49^2 .

It is a cyclic number.

It is not a de Polignac number, because 20357 - 2² = 20353 is a prime.

Together with 20359, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 20357.

It is not a weakly prime, because it can be changed into another prime (20353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10178 + 10179.

It is an arithmetic number, because the mean of its divisors is an integer number (10179).

2²⁰³⁵⁷ is an apocalyptic number.

It is an amenable number.

20357 is a deficient number, since it is larger than the sum of its proper divisors (1).

20357 is an equidigital number, since it uses as much as digits as its factorization.

20357 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 210, while the sum is 17.

The square root of 20357 is about 142.6779590546. The cubic root of 20357 is about 27.3047324601.

Adding to 20357 its reverse (75302), we get a palindrome (95659).

Subtracting 20357 from its reverse (75302), we obtain a palindrome (54945).

It can be divided in two parts, 20 and 357, that multiplied together give a triangular number (7140 = T₁₁₉).

The spelling of 20357 in words is "twenty thousand, three hundred fifty-seven".