681994871 has 2 divisors, whose sum is σ = 681994872. Its totient is φ = 681994870.

The previous prime is 681994867. The next prime is 681994877. The reversal of 681994871 is 178499186.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 681994871 - 2² = 681994867 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681994877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340997435 + 340997436.

It is an arithmetic number, because the mean of its divisors is an integer number (340997436).

Almost surely, 2^681994871 is an apocalyptic number.

681994871 is a deficient number, since it is larger than the sum of its proper divisors (1).

681994871 is an equidigital number, since it uses as much as digits as its factorization.

681994871 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 53.

The square root of 681994871 is about 26115.0315144363. The cubic root of 681994871 is about 880.2250074594.

The spelling of 681994871 in words is "six hundred eighty-one million, nine hundred ninety-four thousand, eight hundred seventy-one".