681556 has 6 divisors (see below), whose sum is σ = 1192730. Its totient is φ = 340776.

The previous prime is 681539. The next prime is 681557. The reversal of 681556 is 655186.

It can be written as a sum of positive squares in only one way, i.e., 547600 + 133956 = 740^2 + 366^2 .

It is a super-2 number, since 2×681556² = 929037162272, which contains 22 as substring.

It is a nialpdrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681557) by changing a digit.

681556 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85191 + ... + 85198.

2⁶⁸¹⁵⁵⁶ is an apocalyptic number.

It is an amenable number.

681556 is a deficient number, since it is larger than the sum of its proper divisors (511174).

681556 is a wasteful number, since it uses less digits than its factorization.

681556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170393 (or 170391 counting only the distinct ones).

The product of its digits is 7200, while the sum is 31.

The square root of 681556 is about 825.5640496049. The cubic root of 681556 is about 88.0036155539.

The spelling of 681556 in words is "six hundred eighty-one thousand, five hundred fifty-six".