18997777 has 4 divisors (see below), whose sum is σ = 19997680. Its totient is φ = 17997876.

The previous prime is 18997757. The next prime is 18997799. The reversal of 18997777 is 77779981.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18997777 - 2¹¹ = 18995729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18997717) 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, 499923 + ... + 499960.

It is an arithmetic number, because the mean of its divisors is an integer number (4999420).

Almost surely, 2^18997777 is an apocalyptic number.

It is an amenable number.

18997777 is a deficient number, since it is larger than the sum of its proper divisors (999903).

18997777 is an equidigital number, since it uses as much as digits as its factorization.

18997777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 999902.

The product of its digits is 1555848, while the sum is 55.

The square root of 18997777 is about 4358.6439404934. The cubic root of 18997777 is about 266.8297576999.

The spelling of 18997777 in words is "eighteen million, nine hundred ninety-seven thousand, seven hundred seventy-seven".