16646656 has 80 divisors (see below), whose sum is σ = 37294488. Its totient is φ = 7372800.

The previous prime is 16646639. The next prime is 16646657. The reversal of 16646656 is 65664661.

It can be written as a sum of positive squares in 4 ways, for example, as 2509056 + 14137600 = 1584^2 + 3760^2 .

It is a super-2 number, since 2×16646656² = 554222311964672, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16646657) by changing a digit.

It is a nontrivial repunit in base 255.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 272866 + ... + 272926.

Almost surely, 2^16646656 is an apocalyptic number.

16646656 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 16646656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18647244).

16646656 is an abundant number, since it is smaller than the sum of its proper divisors (20647832).

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

16646656 is an equidigital number, since it uses as much as digits as its factorization.

16646656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133 (or 117 counting only the distinct ones).

The product of its digits is 155520, while the sum is 40.

The square root of 16646656 is about 4080.0313724284. The cubic root of 16646656 is about 255.3342074397.

It can be divided in two parts, 1664 and 6656, that multiplied together give a square (11075584 = 3328²).

The spelling of 16646656 in words is "sixteen million, six hundred forty-six thousand, six hundred fifty-six".