16509985994656 has 384 divisors, whose sum is σ = 42046237900800. Its totient is φ = 6193152000000.

The previous prime is 16509985994653. The next prime is 16509985994693. The reversal of 16509985994656 is 65649958990561.

It is a super-3 number, since 3×16509985994656³ (a number of 41 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16509985994656.

It is not an unprimeable number, because it can be changed into a prime (16509985994653) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 21984002281 + ... + 21984003031.

It is an arithmetic number, because the mean of its divisors is an integer number (109495411200).

Almost surely, 2^{16509985994656} is an apocalyptic number.

16509985994656 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 16509985994656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21023118950400).

16509985994656 is an abundant number, since it is smaller than the sum of its proper divisors (25536251906144).

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

16509985994656 is a wasteful number, since it uses less digits than its factorization.

16509985994656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1900 (or 1892 counting only the distinct ones).

The product of its (nonzero) digits is 5668704000, while the sum is 82.

The spelling of 16509985994656 in words is "sixteen trillion, five hundred nine billion, nine hundred eighty-five million, nine hundred ninety-four thousand, six hundred fifty-six".