16686891648 has 448 divisors, whose sum is σ = 58061908800. Its totient is φ = 4676050944.

The previous prime is 16686891643. The next prime is 16686891659. The reversal of 16686891648 is 84619868661.

It is a tau number, because it is divible by the number of its divisors (448).

It is a Smith number, since the sum of its digits (63) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (16686891643) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 38537640 + ... + 38538072.

It is an arithmetic number, because the mean of its divisors is an integer number (129602475).

Almost surely, 2^16686891648 is an apocalyptic number.

16686891648 is a gapful number since it is divisible by the number (18) 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 16686891648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29030954400).

16686891648 is an abundant number, since it is smaller than the sum of its proper divisors (41375017152).

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

16686891648 is an frugal number, since it uses more digits than its factorization.

16686891648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 531 (or 504 counting only the distinct ones).

The product of its digits is 23887872, while the sum is 63.

It can be divided in two parts, 1668689 and 1648, that multiplied together give a palindrome (2749999472).

The spelling of 16686891648 in words is "sixteen billion, six hundred eighty-six million, eight hundred ninety-one thousand, six hundred forty-eight".