1638489216 has 128 divisors (see below), whose sum is σ = 5356713600. Its totient is φ = 432119808.

The previous prime is 1638489197. The next prime is 1638489217. The reversal of 1638489216 is 6129848361.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (1638489217) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11500 + ... + 58388.

It is an arithmetic number, because the mean of its divisors is an integer number (41849325).

Almost surely, 2^1638489216 is an apocalyptic number.

1638489216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1638489216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2678356800).

1638489216 is an abundant number, since it is smaller than the sum of its proper divisors (3718224384).

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

1638489216 is a wasteful number, since it uses less digits than its factorization.

1638489216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46926 (or 46914 counting only the distinct ones).

The product of its digits is 497664, while the sum is 48.

The square root of 1638489216 is about 40478.2560889177. The cubic root of 1638489216 is about 1178.9114772595.

The spelling of 1638489216 in words is "one billion, six hundred thirty-eight million, four hundred eighty-nine thousand, two hundred sixteen".