1209999 has 16 divisors (see below), whose sum is σ = 1860608. Its totient is φ = 685152.

The previous prime is 1209979. The next prime is 1210003. The reversal of 1209999 is 9999021.

It is a happy number.

It is a Cunningham number, because it is equal to 1100²-1.

It is not a de Polignac number, because 1209999 - 2⁹ = 1209487 is a prime.

It is a Smith number, since the sum of its digits (39) 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.

1209999 is a modest number, since divided by 9999 gives 120 as remainder.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1209959) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3114 + ... + 3480.

It is an arithmetic number, because the mean of its divisors is an integer number (116288).

2^1209999 is an apocalyptic number.

1209999 is a deficient number, since it is larger than the sum of its proper divisors (650609).

1209999 is a wasteful number, since it uses less digits than its factorization.

1209999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534.

The product of its (nonzero) digits is 13122, while the sum is 39.

The square root of 1209999 is about 1099.9995454545. Note that the first 3 decimals coincide. The cubic root of 1209999 is about 106.5601943212.

The spelling of 1209999 in words is "one million, two hundred nine thousand, nine hundred ninety-nine".