66765989 has 4 divisors (see below), whose sum is σ = 66910656. Its totient is φ = 66621324.

The previous prime is 66765983. The next prime is 66765997. The reversal of 66765989 is 98956766.

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-66765989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66765983) 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, 71639 + ... + 72564.

It is an arithmetic number, because the mean of its divisors is an integer number (16727664).

Almost surely, 2^66765989 is an apocalyptic number.

It is an amenable number.

66765989 is a deficient number, since it is larger than the sum of its proper divisors (144667).

66765989 is a wasteful number, since it uses less digits than its factorization.

66765989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144666.

The product of its digits is 4898880, while the sum is 56.

The square root of 66765989 is about 8171.0457715032. The cubic root of 66765989 is about 405.6813992848.

The spelling of 66765989 in words is "sixty-six million, seven hundred sixty-five thousand, nine hundred eighty-nine".