66501009 has 12 divisors (see below), whose sum is σ = 96939700. Its totient is φ = 43926624.

The previous prime is 66500939. The next prime is 66501049. The reversal of 66501009 is 90010566.

66501009 is a `hidden beast` number, since 6 + 650 + 1 + 0 + 0 + 9 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 55130625 + 11370384 = 7425^2 + 3372^2 .

It is not a de Polignac number, because 66501009 - 2⁷ = 66500881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66501049) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32914 + ... + 34875.

Almost surely, 2^66501009 is an apocalyptic number.

It is an amenable number.

66501009 is a deficient number, since it is larger than the sum of its proper divisors (30438691).

66501009 is a wasteful number, since it uses less digits than its factorization.

66501009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67904 (or 67901 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 66501009 is about 8154.8150806747. The cubic root of 66501009 is about 405.1440000056.

The spelling of 66501009 in words is "sixty-six million, five hundred one thousand, nine".