65666840 has 64 divisors (see below), whose sum is σ = 155597760. Its totient is φ = 24893440.

The previous prime is 65666813. The next prime is 65666851. The reversal of 65666840 is 4866656.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 125780 + ... + 126300.

It is an arithmetic number, because the mean of its divisors is an integer number (2431215).

Almost surely, 2^65666840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65666840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77798880).

65666840 is an abundant number, since it is smaller than the sum of its proper divisors (89930920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

65666840 is a wasteful number, since it uses less digits than its factorization.

65666840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 692 (or 688 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 41.

The square root of 65666840 is about 8103.5078823927. The cubic root of 65666840 is about 403.4428650150.

The spelling of 65666840 in words is "sixty-five million, six hundred sixty-six thousand, eight hundred forty".