647 has 2 divisors, whose sum is σ = 648. Its totient is φ = 646.

The previous prime is 643. The next prime is 653. The reversal of 647 is 746.

Subtracting from 647 its sum of digits (17), we obtain a triangular number (630 = T_{35}).

Subtracting 647 from its reverse (746), we obtain a palindrome (99).

It can be divided in two parts, 6 and 47, that multiplied together give a palindrome (282).

647 is nontrivially palindromic in base 14 and base 15.

647 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

647 is an esthetic number in base 14, because in such base its adjacent digits differ by 1.

It is a weak prime.

647 is a truncatable prime.

It is a cyclic number.

It is not a de Polignac number, because 647 - 2^{2} = 643 is a prime.

It is a Chen prime.

It is a magnanimous number.

647 is an undulating number in base 14 and base 15.

It is a plaindrome in base 6, base 9, base 12 and base 13.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323 + 324.

It is an arithmetic number, because the mean of its divisors is an integer number (324).

2^{647} is an apocalyptic number.

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

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

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

The product of its digits is 168, while the sum is 17.

The square root of 647 is about 25.4361946840. The cubic root of 647 is about 8.6490437425.

The spelling of 647 in words is "six hundred forty-seven", and thus it is an aban number.

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