18445172779 has 4 divisors (see below), whose sum is σ = 20122006680. Its totient is φ = 16768338880.

The previous prime is 18445172761. The next prime is 18445172791. The reversal of 18445172779 is 97727154481.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97727154481 = 11 ⋅8884286771.

It is a cyclic number.

It is not a de Polignac number, because 18445172779 - 2⁷ = 18445172651 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18445172719) 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, 838416934 + ... + 838416955.

It is an arithmetic number, because the mean of its divisors is an integer number (5030501670).

Almost surely, 2^18445172779 is an apocalyptic number.

18445172779 is a deficient number, since it is larger than the sum of its proper divisors (1676833901).

18445172779 is a wasteful number, since it uses less digits than its factorization.

18445172779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1676833900.

The product of its digits is 3951360, while the sum is 55.

The spelling of 18445172779 in words is "eighteen billion, four hundred forty-five million, one hundred seventy-two thousand, seven hundred seventy-nine".