681706646 has 4 divisors (see below), whose sum is σ = 1022559972. Its totient is φ = 340853322.

The previous prime is 681706621. The next prime is 681706661. The reversal of 681706646 is 646607186.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 646607186 = 2 ⋅323303593.

It is a junction number, because it is equal to n+sod(n) for n = 681706597 and 681706606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 170426660 + ... + 170426663.

It is an arithmetic number, because the mean of its divisors is an integer number (255639993).

Almost surely, 2^681706646 is an apocalyptic number.

681706646 is a deficient number, since it is larger than the sum of its proper divisors (340853326).

681706646 is a wasteful number, since it uses less digits than its factorization.

681706646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340853325.

The product of its (nonzero) digits is 290304, while the sum is 44.

The square root of 681706646 is about 26109.5125576867. The cubic root of 681706646 is about 880.1009896151.

The spelling of 681706646 in words is "six hundred eighty-one million, seven hundred six thousand, six hundred forty-six".