66940399 has 4 divisors (see below), whose sum is σ = 66964360. Its totient is φ = 66916440.

The previous prime is 66940387. The next prime is 66940411. The reversal of 66940399 is 99304966.

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

It is an interprime number because it is at equal distance from previous prime (66940387) and next prime (66940411).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66940399 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 (66940309) 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, 7137 + ... + 13594.

It is an arithmetic number, because the mean of its divisors is an integer number (16741090).

Almost surely, 2^66940399 is an apocalyptic number.

66940399 is a deficient number, since it is larger than the sum of its proper divisors (23961).

66940399 is a wasteful number, since it uses less digits than its factorization.

66940399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23960.

The product of its (nonzero) digits is 314928, while the sum is 46.

The square root of 66940399 is about 8181.7112513214. The cubic root of 66940399 is about 406.0343403213.

The spelling of 66940399 in words is "sixty-six million, nine hundred forty thousand, three hundred ninety-nine".