66399331 has 4 divisors (see below), whose sum is σ = 70305192. Its totient is φ = 62493472.

The previous prime is 66399329. The next prime is 66399337. The reversal of 66399331 is 13399366.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66399331 - 2¹ = 66399329 is a prime.

It is a super-2 number, since 2×66399331² = 8817742314495122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66399337) 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, 1952905 + ... + 1952938.

It is an arithmetic number, because the mean of its divisors is an integer number (17576298).

Almost surely, 2^66399331 is an apocalyptic number.

66399331 is a deficient number, since it is larger than the sum of its proper divisors (3905861).

66399331 is a wasteful number, since it uses less digits than its factorization.

66399331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3905860.

The product of its digits is 78732, while the sum is 40.

The square root of 66399331 is about 8148.5784649839. The cubic root of 66399331 is about 404.9374104365.

The spelling of 66399331 in words is "sixty-six million, three hundred ninety-nine thousand, three hundred thirty-one".