25643 has 2 divisors, whose sum is σ = 25644. Its totient is φ = 25642.

The previous prime is 25639. The next prime is 25657. The reversal of 25643 is 34652.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 25643 - 2² = 25639 is a prime.

It is a Sophie Germain prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (25603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12821 + 12822.

It is an arithmetic number, because the mean of its divisors is an integer number (12822).

2²⁵⁶⁴³ is an apocalyptic number.

25643 is a deficient number, since it is larger than the sum of its proper divisors (1).

25643 is an equidigital number, since it uses as much as digits as its factorization.

25643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 720, while the sum is 20.

The square root of 25643 is about 160.1343186203. The cubic root of 25643 is about 29.4887441498.

Subtracting 25643 from its reverse (34652), we obtain a palindrome (9009).

The spelling of 25643 in words is "twenty-five thousand, six hundred forty-three".