66517840 has 40 divisors (see below), whose sum is σ = 161382528. Its totient is φ = 25449600.

The previous prime is 66517837. The next prime is 66517849. The reversal of 66517840 is 4871566.

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 66517840.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66517849) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 16236 + ... + 19915.

Almost surely, 2^66517840 is an apocalyptic number.

It is an amenable number.

66517840 is an abundant number, since it is smaller than the sum of its proper divisors (94864688).

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

66517840 is a wasteful number, since it uses less digits than its factorization.

66517840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36187 (or 36181 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 37.

The square root of 66517840 is about 8155.8469823802. The cubic root of 66517840 is about 405.1781769480.

The spelling of 66517840 in words is "sixty-six million, five hundred seventeen thousand, eight hundred forty".