64673681 has 4 divisors (see below), whose sum is σ = 64835364. Its totient is φ = 64512000.

The previous prime is 64673579. The next prime is 64673711. The reversal of 64673681 is 18637646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18637646 = 2 ⋅9318823.

It can be written as a sum of positive squares in 2 ways, for example, as 49000000 + 15673681 = 7000^2 + 3959^2 .

It is a cyclic number.

It is not a de Polignac number, because 64673681 - 2¹⁸ = 64411537 is a prime.

It is a super-2 number, since 2×64673681² = 8365370028179522, 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 (64673981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80240 + ... + 81041.

It is an arithmetic number, because the mean of its divisors is an integer number (16208841).

Almost surely, 2^64673681 is an apocalyptic number.

It is an amenable number.

64673681 is a deficient number, since it is larger than the sum of its proper divisors (161683).

64673681 is a wasteful number, since it uses less digits than its factorization.

64673681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161682.

The product of its digits is 145152, while the sum is 41.

The square root of 64673681 is about 8041.9948395905. The cubic root of 64673681 is about 401.3986061359.

The spelling of 64673681 in words is "sixty-four million, six hundred seventy-three thousand, six hundred eighty-one".