66912971 has 4 divisors (see below), whose sum is σ = 66940512. Its totient is φ = 66885432.

The previous prime is 66912961. The next prime is 66912991. The reversal of 66912971 is 17921966.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17921966 = 2 ⋅8960983.

It is a cyclic number.

It is not a de Polignac number, because 66912971 - 2¹⁸ = 66650827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66912961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9731 + ... + 15116.

It is an arithmetic number, because the mean of its divisors is an integer number (16735128).

Almost surely, 2^66912971 is an apocalyptic number.

66912971 is a deficient number, since it is larger than the sum of its proper divisors (27541).

66912971 is a wasteful number, since it uses less digits than its factorization.

66912971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27540.

The product of its digits is 40824, while the sum is 41.

The square root of 66912971 is about 8180.0349021260. The cubic root of 66912971 is about 405.9788768969.

The spelling of 66912971 in words is "sixty-six million, nine hundred twelve thousand, nine hundred seventy-one".