681647 has 2 divisors, whose sum is σ = 681648. Its totient is φ = 681646.

The previous prime is 681631. The next prime is 681673. The reversal of 681647 is 746186.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 681647 - 2⁴ = 681631 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340823 + 340824.

It is an arithmetic number, because the mean of its divisors is an integer number (340824).

2⁶⁸¹⁶⁴⁷ is an apocalyptic number.

681647 is a deficient number, since it is larger than the sum of its proper divisors (1).

681647 is an equidigital number, since it uses as much as digits as its factorization.

681647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8064, while the sum is 32.

The square root of 681647 is about 825.6191615993. The cubic root of 681647 is about 88.0075320688.

The spelling of 681647 in words is "six hundred eighty-one thousand, six hundred forty-seven".