681660 has 72 divisors (see below), whose sum is σ = 2367456. Its totient is φ = 155520.

The previous prime is 681647. The next prime is 681673. The reversal of 681660 is 66186.

It is an interprime number because it is at equal distance from previous prime (681647) and next prime (681673).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a zygodrome in base 6.

It is a congruent number.

It is an unprimeable number.

681660 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 990 + ... + 1530.

2⁶⁸¹⁶⁶⁰ is an apocalyptic number.

681660 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 681660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1183728).

681660 is an abundant number, since it is smaller than the sum of its proper divisors (1685796).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

681660 is a wasteful number, since it uses less digits than its factorization.

681660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563 (or 558 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 681660 is about 825.6270344411. The cubic root of 681660 is about 88.0080915425.

It can be divided in two parts, 68 and 1660, that added together give a cube (1728 = 12³).

The spelling of 681660 in words is "six hundred eighty-one thousand, six hundred sixty".