18399779 has 4 divisors (see below), whose sum is σ = 18411360. Its totient is φ = 18388200.

The previous prime is 18399751. The next prime is 18399781. The reversal of 18399779 is 97799381.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 97799381 = 23 ⋅4252147.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18399779 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 18399779.

It is not an unprimeable number, because it can be changed into a prime (18399749) 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, 2939 + ... + 6740.

It is an arithmetic number, because the mean of its divisors is an integer number (4602840).

Almost surely, 2^18399779 is an apocalyptic number.

18399779 is a deficient number, since it is larger than the sum of its proper divisors (11581).

18399779 is an equidigital number, since it uses as much as digits as its factorization.

18399779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11580.

The product of its digits is 857304, while the sum is 53.

The square root of 18399779 is about 4289.4963573828. The cubic root of 18399779 is about 264.0001673935. Note that the first 3 decimals are identical.

The spelling of 18399779 in words is "eighteen million, three hundred ninety-nine thousand, seven hundred seventy-nine".