1209999979 has 4 divisors (see below), whose sum is σ = 1224578376. Its totient is φ = 1195421584.

The previous prime is 1209999943. The next prime is 1209999997. The reversal of 1209999979 is 9799999021.

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

It is a cyclic number.

It is not a de Polignac number, because 1209999979 - 2⁷ = 1209999851 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1209999979.

It is not an unprimeable number, because it can be changed into a prime (1209999079) 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, 7289074 + ... + 7289239.

It is an arithmetic number, because the mean of its divisors is an integer number (306144594).

Almost surely, 2^1209999979 is an apocalyptic number.

1209999979 is a deficient number, since it is larger than the sum of its proper divisors (14578397).

1209999979 is an equidigital number, since it uses as much as digits as its factorization.

1209999979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14578396.

The product of its (nonzero) digits is 7440174, while the sum is 64.

The square root of 1209999979 is about 34785.0539599984. The cubic root of 1209999979 is about 1065.6022306020.

The spelling of 1209999979 in words is "one billion, two hundred nine million, nine hundred ninety-nine thousand, nine hundred seventy-nine".