66971689 has 4 divisors (see below), whose sum is σ = 66999040. Its totient is φ = 66944340.

The previous prime is 66971669. The next prime is 66971693. The reversal of 66971689 is 98617966.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66971689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66971609) 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, 9597 + ... + 15034.

It is an arithmetic number, because the mean of its divisors is an integer number (16749760).

Almost surely, 2^66971689 is an apocalyptic number.

It is an amenable number.

66971689 is a deficient number, since it is larger than the sum of its proper divisors (27351).

66971689 is a wasteful number, since it uses less digits than its factorization.

66971689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27350.

The product of its digits is 979776, while the sum is 52.

The square root of 66971689 is about 8183.6232195770. The cubic root of 66971689 is about 406.0975947769.

The spelling of 66971689 in words is "sixty-six million, nine hundred seventy-one thousand, six hundred eighty-nine".