66718509 has 16 divisors (see below), whose sum is σ = 104510784. Its totient is φ = 37324800.

The previous prime is 66718507. The next prime is 66718517. The reversal of 66718509 is 90581766.

It is not a de Polignac number, because 66718509 - 2¹ = 66718507 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66718501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77332 + ... + 78189.

It is an arithmetic number, because the mean of its divisors is an integer number (6531924).

Almost surely, 2^66718509 is an apocalyptic number.

It is an amenable number.

66718509 is a deficient number, since it is larger than the sum of its proper divisors (37792275).

66718509 is a wasteful number, since it uses less digits than its factorization.

66718509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155548.

The product of its (nonzero) digits is 90720, while the sum is 42.

The square root of 66718509 is about 8168.1398739248. The cubic root of 66718509 is about 405.5852109866.

The spelling of 66718509 in words is "sixty-six million, seven hundred eighteen thousand, five hundred nine".