1966399 has 2 divisors, whose sum is σ = 1966400. Its totient is φ = 1966398.

The previous prime is 1966397. The next prime is 1966409. The reversal of 1966399 is 9936691.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1966399 - 2¹ = 1966397 is a prime.

Together with 1966397, it forms a pair of twin primes.

1966399 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1966397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 983199 + 983200.

It is an arithmetic number, because the mean of its divisors is an integer number (983200).

2^1966399 is an apocalyptic number.

1966399 is a deficient number, since it is larger than the sum of its proper divisors (1).

1966399 is an equidigital number, since it uses as much as digits as its factorization.

1966399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 78732, while the sum is 43.

The square root of 1966399 is about 1402.2834948754. The cubic root of 1966399 is about 125.2825395567.

The spelling of 1966399 in words is "one million, nine hundred sixty-six thousand, three hundred ninety-nine".