66805720 has 32 divisors (see below), whose sum is σ = 154378800. Its totient is φ = 25999488.

The previous prime is 66805709. The next prime is 66805727. The reversal of 66805720 is 2750866.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66805727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21090 + ... + 24049.

Almost surely, 2^66805720 is an apocalyptic number.

It is an amenable number.

66805720 is an abundant number, since it is smaller than the sum of its proper divisors (87573080).

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

66805720 is a wasteful number, since it uses less digits than its factorization.

66805720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45187 (or 45183 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 66805720 is about 8173.4766164711. The cubic root of 66805720 is about 405.7618540782.

The spelling of 66805720 in words is "sixty-six million, eight hundred five thousand, seven hundred twenty".