66688931 has 8 divisors (see below), whose sum is σ = 67754400. Its totient is φ = 65627712.

The previous prime is 66688903. The next prime is 66688957. The reversal of 66688931 is 13988666.

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

It is a cyclic number.

It is not a de Polignac number, because 66688931 - 2¹⁴ = 66672547 is a prime.

It is a super-2 number, since 2×66688931² = 8894827035845522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66688961) 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 7 ways as a sum of consecutive naturals, for example, 46970 + ... + 48368.

It is an arithmetic number, because the mean of its divisors is an integer number (8469300).

Almost surely, 2^66688931 is an apocalyptic number.

66688931 is a deficient number, since it is larger than the sum of its proper divisors (1065469).

66688931 is a wasteful number, since it uses less digits than its factorization.

66688931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2125.

The product of its digits is 373248, while the sum is 47.

The square root of 66688931 is about 8166.3291018670. The cubic root of 66688931 is about 405.5252667385.

The spelling of 66688931 in words is "sixty-six million, six hundred eighty-eight thousand, nine hundred thirty-one".