66709391 has 8 divisors (see below), whose sum is σ = 76297344. Its totient is φ = 57135960.

The previous prime is 66709381. The next prime is 66709393. The reversal of 66709391 is 19390766.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-66709391 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66709393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9296 + ... + 14826.

It is an arithmetic number, because the mean of its divisors is an integer number (9537168).

Almost surely, 2^66709391 is an apocalyptic number.

66709391 is a deficient number, since it is larger than the sum of its proper divisors (9587953).

66709391 is a wasteful number, since it uses less digits than its factorization.

66709391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7261.

The product of its (nonzero) digits is 61236, while the sum is 41.

The square root of 66709391 is about 8167.5817106412. The cubic root of 66709391 is about 405.5667338829.

It can be divided in two parts, 6670 and 9391, that added together give a palindrome (16061).

The spelling of 66709391 in words is "sixty-six million, seven hundred nine thousand, three hundred ninety-one".