681949761 has 24 divisors (see below), whose sum is σ = 964328640. Its totient is φ = 428158080.

The previous prime is 681949727. The next prime is 681949799. The reversal of 681949761 is 167949186.

It is a happy number.

It is not a de Polignac number, because 681949761 - 2¹¹ = 681947713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (681949711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 143916 + ... + 148578.

It is an arithmetic number, because the mean of its divisors is an integer number (40180360).

Almost surely, 2^681949761 is an apocalyptic number.

It is an amenable number.

681949761 is a deficient number, since it is larger than the sum of its proper divisors (282378879).

681949761 is a wasteful number, since it uses less digits than its factorization.

681949761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4777 (or 4736 counting only the distinct ones).

The product of its digits is 653184, while the sum is 51.

The square root of 681949761 is about 26114.1678213188. The cubic root of 681949761 is about 880.2055997741.

The spelling of 681949761 in words is "six hundred eighty-one million, nine hundred forty-nine thousand, seven hundred sixty-one".