66840728 has 8 divisors (see below), whose sum is σ = 125326380. Its totient is φ = 33420360.

The previous prime is 66840713. The next prime is 66840731. The reversal of 66840728 is 82704866.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4177538 + ... + 4177553.

Almost surely, 2^66840728 is an apocalyptic number.

It is an amenable number.

66840728 is a deficient number, since it is larger than the sum of its proper divisors (58485652).

66840728 is a wasteful number, since it uses less digits than its factorization.

66840728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8355097 (or 8355093 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 41.

The square root of 66840728 is about 8175.6178971378. The cubic root of 66840728 is about 405.8327184216.

The spelling of 66840728 in words is "sixty-six million, eight hundred forty thousand, seven hundred twenty-eight".