65681681 has 12 divisors (see below), whose sum is σ = 72474588. Its totient is φ = 59477184.

The previous prime is 65681669. The next prime is 65681687. The reversal of 65681681 is 18618656.

It is a happy number.

65681681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 6 ways, for example, as 22648081 + 43033600 = 4759^2 + 6560^2 .

It is not a de Polignac number, because 65681681 - 2⁶ = 65681617 is a prime.

It is a super-2 number, since 2×65681681² = 8628166437971522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (65681687) 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 11 ways as a sum of consecutive naturals, for example, 5291 + ... + 12623.

It is an arithmetic number, because the mean of its divisors is an integer number (6039549).

Almost surely, 2^65681681 is an apocalyptic number.

It is an amenable number.

65681681 is a deficient number, since it is larger than the sum of its proper divisors (6792907).

65681681 is a wasteful number, since it uses less digits than its factorization.

65681681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7412 (or 7399 counting only the distinct ones).

The product of its digits is 69120, while the sum is 41.

The square root of 65681681 is about 8104.4235452005. The cubic root of 65681681 is about 403.4732560239.

The spelling of 65681681 in words is "sixty-five million, six hundred eighty-one thousand, six hundred eighty-one".