66669399 has 20 divisors (see below), whose sum is σ = 99822096. Its totient is φ = 44343936.

The previous prime is 66669371. The next prime is 66669409. The reversal of 66669399 is 99396666.

It is not a de Polignac number, because 66669399 - 2⁸ = 66669143 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66669319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 53902 + ... + 55124.

Almost surely, 2^66669399 is an apocalyptic number.

66669399 is a deficient number, since it is larger than the sum of its proper divisors (33152697).

66669399 is a wasteful number, since it uses less digits than its factorization.

66669399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1908 (or 1899 counting only the distinct ones).

The product of its digits is 2834352, while the sum is 54.

The square root of 66669399 is about 8165.1331281247. The cubic root of 66669399 is about 405.4856724970.

The spelling of 66669399 in words is "sixty-six million, six hundred sixty-nine thousand, three hundred ninety-nine".