681645727 has 4 divisors (see below), whose sum is σ = 779023696. Its totient is φ = 584267760.

The previous prime is 681645721. The next prime is 681645803. The reversal of 681645727 is 727546186.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 727546186 = 2 ⋅363773093.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681645727 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681645721) 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, 48688974 + ... + 48688987.

It is an arithmetic number, because the mean of its divisors is an integer number (194755924).

Almost surely, 2^681645727 is an apocalyptic number.

681645727 is a deficient number, since it is larger than the sum of its proper divisors (97377969).

681645727 is an equidigital number, since it uses as much as digits as its factorization.

681645727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97377968.

The product of its digits is 564480, while the sum is 46.

The square root of 681645727 is about 26108.3459261593. The cubic root of 681645727 is about 880.0747728303.

The spelling of 681645727 in words is "six hundred eighty-one million, six hundred forty-five thousand, seven hundred twenty-seven".