18977689949 has 4 divisors (see below), whose sum is σ = 18980403036. Its totient is φ = 18974976864.

The previous prime is 18977689889. The next prime is 18977689981. The reversal of 18977689949 is 94998677981.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15865165849 + 3112524100 = 125957^2 + 55790^2 .

It is a cyclic number.

It is not a de Polignac number, because 18977689949 - 2²⁸ = 18709254493 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 18977689949.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18977689249) 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, 1346024 + ... + 1360049.

It is an arithmetic number, because the mean of its divisors is an integer number (4745100759).

Almost surely, 2^18977689949 is an apocalyptic number.

It is an amenable number.

18977689949 is a deficient number, since it is larger than the sum of its proper divisors (2713087).

18977689949 is an equidigital number, since it uses as much as digits as its factorization.

18977689949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2713086.

The product of its digits is 493807104, while the sum is 77.

The spelling of 18977689949 in words is "eighteen billion, nine hundred seventy-seven million, six hundred eighty-nine thousand, nine hundred forty-nine".