18977728 has 56 divisors (see below), whose sum is σ = 46963584. Its totient is φ = 7392000.

The previous prime is 18977723. The next prime is 18977731. The reversal of 18977728 is 82777981.

It is a tau number, because it is divible by the number of its divisors (56).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18977723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3003 + ... + 6853.

Almost surely, 2^18977728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18977728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23481792).

18977728 is an abundant number, since it is smaller than the sum of its proper divisors (27985856).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18977728 is a wasteful number, since it uses less digits than its factorization.

18977728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3881 (or 3871 counting only the distinct ones).

The product of its digits is 395136, while the sum is 49.

The square root of 18977728 is about 4356.3434208060. The cubic root of 18977728 is about 266.7358598224.

The spelling of 18977728 in words is "eighteen million, nine hundred seventy-seven thousand, seven hundred twenty-eight".