681643161 has 8 divisors (see below), whose sum is σ = 1009841760. Its totient is φ = 454428756.

The previous prime is 681643141. The next prime is 681643177. The reversal of 681643161 is 161346186.

681643161 is a `hidden beast` number, since 6 + 8 + 1 + 643 + 1 + 6 + 1 = 666.

It is not a de Polignac number, because 681643161 - 2¹⁸ = 681381017 is a prime.

It is not an unprimeable number, because it can be changed into a prime (681643141) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 12622995 + ... + 12623048.

It is an arithmetic number, because the mean of its divisors is an integer number (126230220).

Almost surely, 2^681643161 is an apocalyptic number.

It is an amenable number.

681643161 is a deficient number, since it is larger than the sum of its proper divisors (328198599).

681643161 is a wasteful number, since it uses less digits than its factorization.

681643161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25246052 (or 25246046 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 681643161 is about 26108.2967847388. The cubic root of 681643161 is about 880.0736685056.

The spelling of 681643161 in words is "six hundred eighty-one million, six hundred forty-three thousand, one hundred sixty-one".