66631809 has 8 divisors (see below), whose sum is σ = 89657920. Its totient is φ = 44013456.

The previous prime is 66631801. The next prime is 66631813. The reversal of 66631809 is 90813666.

It is a happy number.

66631809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66631809 - 2³ = 66631801 is a prime.

It is a super-2 number, since 2×66631809² = 8879595941224962, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (66631801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 101557 + ... + 102210.

It is an arithmetic number, because the mean of its divisors is an integer number (11207240).

Almost surely, 2^66631809 is an apocalyptic number.

It is an amenable number.

66631809 is a deficient number, since it is larger than the sum of its proper divisors (23026111).

66631809 is a wasteful number, since it uses less digits than its factorization.

66631809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203879.

The product of its (nonzero) digits is 46656, while the sum is 39.

The square root of 66631809 is about 8162.8309427551. The cubic root of 66631809 is about 405.4094502610.

The spelling of 66631809 in words is "sixty-six million, six hundred thirty-one thousand, eight hundred nine".