66397691 has 8 divisors (see below), whose sum is σ = 68871168. Its totient is φ = 63945000.

The previous prime is 66397687. The next prime is 66397717. The reversal of 66397691 is 19679366.

It is a happy number.

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 66397691 - 2² = 66397687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66397601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1466 + ... + 11616.

It is an arithmetic number, because the mean of its divisors is an integer number (8608896).

Almost surely, 2^66397691 is an apocalyptic number.

66397691 is a deficient number, since it is larger than the sum of its proper divisors (2473477).

66397691 is a wasteful number, since it uses less digits than its factorization.

66397691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10393.

The product of its digits is 367416, while the sum is 47.

The square root of 66397691 is about 8148.4778333134. The cubic root of 66397691 is about 404.9340765534.

The spelling of 66397691 in words is "sixty-six million, three hundred ninety-seven thousand, six hundred ninety-one".