681569 has 4 divisors (see below), whose sum is σ = 778944. Its totient is φ = 584196.

The previous prime is 681563. The next prime is 681589. The reversal of 681569 is 965186.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 965186 = 2 ⋅482593.

It is a cyclic number.

It is not a de Polignac number, because 681569 - 2¹² = 677473 is a prime.

It is a super-2 number, since 2×681569² = 929072603522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (681563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48677 + ... + 48690.

It is an arithmetic number, because the mean of its divisors is an integer number (194736).

2⁶⁸¹⁵⁶⁹ is an apocalyptic number.

It is an amenable number.

681569 is a deficient number, since it is larger than the sum of its proper divisors (97375).

681569 is an equidigital number, since it uses as much as digits as its factorization.

681569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97374.

The product of its digits is 12960, while the sum is 35.

The square root of 681569 is about 825.5719229722. The cubic root of 681569 is about 88.0041750774.

The spelling of 681569 in words is "six hundred eighty-one thousand, five hundred sixty-nine".