1366399999 has 4 divisors (see below), whose sum is σ = 1368053064. Its totient is φ = 1364746936.

The previous prime is 1366399987. The next prime is 1366400011. The reversal of 1366399999 is 9999936631.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9999936631 = 31 ⋅322578601.

It is an interprime number because it is at equal distance from previous prime (1366399987) and next prime (1366400011).

It is a cyclic number.

It is not a de Polignac number, because 1366399999 - 2²⁵ = 1332845567 is a prime.

It is a Duffinian number.

1366399999 is a modest number, since divided by 99999 gives 13663 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 1366399999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1366399399) 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, 825292 + ... + 826945.

It is an arithmetic number, because the mean of its divisors is an integer number (342013266).

Almost surely, 2^1366399999 is an apocalyptic number.

1366399999 is a deficient number, since it is larger than the sum of its proper divisors (1653065).

1366399999 is an equidigital number, since it uses as much as digits as its factorization.

1366399999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1653064.

The product of its digits is 19131876, while the sum is 64.

The square root of 1366399999 is about 36964.8481533470. The cubic root of 1366399999 is about 1109.6668640194. Note that the first 3 decimals are identical.

The spelling of 1366399999 in words is "one billion, three hundred sixty-six million, three hundred ninety-nine thousand, nine hundred ninety-nine".