18979493777 has 4 divisors (see below), whose sum is σ = 18979918260. Its totient is φ = 18979069296.

The previous prime is 18979493773. The next prime is 18979493779. The reversal of 18979493777 is 77739497981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 77739497981 = 37 ⋅2101067513.

It can be written as a sum of positive squares in 2 ways, for example, as 5669487616 + 13310006161 = 75296^2 + 115369^2 .

It is a cyclic number.

It is not a de Polignac number, because 18979493777 - 2² = 18979493773 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 18979493777.

It is not an unprimeable number, because it can be changed into a prime (18979493773) 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, 136058 + ... + 237635.

It is an arithmetic number, because the mean of its divisors is an integer number (4744979565).

Almost surely, 2^18979493777 is an apocalyptic number.

It is an amenable number.

18979493777 is a deficient number, since it is larger than the sum of its proper divisors (424483).

18979493777 is an equidigital number, since it uses as much as digits as its factorization.

18979493777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 424482.

The product of its digits is 168031584, while the sum is 71.

The spelling of 18979493777 in words is "eighteen billion, nine hundred seventy-nine million, four hundred ninety-three thousand, seven hundred seventy-seven".