66688215 has 32 divisors (see below), whose sum is σ = 116812800. Its totient is φ = 32219520.

The previous prime is 66688211. The next prime is 66688217. The reversal of 66688215 is 51288666.

It is not a de Polignac number, because 66688215 - 2² = 66688211 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66688211) 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 31 ways as a sum of consecutive naturals, for example, 63666 + ... + 64704.

It is an arithmetic number, because the mean of its divisors is an integer number (3650400).

Almost surely, 2^66688215 is an apocalyptic number.

66688215 is a deficient number, since it is larger than the sum of its proper divisors (50124585).

66688215 is a wasteful number, since it uses less digits than its factorization.

66688215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1447.

The product of its digits is 138240, while the sum is 42.

The square root of 66688215 is about 8166.2852632026. The cubic root of 66688215 is about 405.5238154375.

The spelling of 66688215 in words is "sixty-six million, six hundred eighty-eight thousand, two hundred fifteen".