66781568 has 64 divisors (see below), whose sum is σ = 154281120. Its totient is φ = 28200960.

The previous prime is 66781543. The next prime is 66781571. The reversal of 66781568 is 86518766.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64898 + ... + 65918.

Almost surely, 2^66781568 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 66781568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77140560).

66781568 is an abundant number, since it is smaller than the sum of its proper divisors (87499552).

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

66781568 is a wasteful number, since it uses less digits than its factorization.

66781568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1115 (or 1103 counting only the distinct ones).

The product of its digits is 483840, while the sum is 47.

The square root of 66781568 is about 8171.9990210474. Note that the first 3 decimals coincide. The cubic root of 66781568 is about 405.7129503739.

The spelling of 66781568 in words is "sixty-six million, seven hundred eighty-one thousand, five hundred sixty-eight".