16721568 has 36 divisors (see below), whose sum is σ = 47552778. Its totient is φ = 5573760.

The previous prime is 16721479. The next prime is 16721569. The reversal of 16721568 is 86512761.

It can be written as a sum of positive squares in only one way, i.e., 15776784 + 944784 = 3972^2 + 972^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×16721568² = 559221672757248, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) 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 (36).

It is not an unprimeable number, because it can be changed into a prime (16721569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 28743 + ... + 29318.

Almost surely, 2^16721568 is an apocalyptic number.

16721568 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

16721568 is an abundant number, since it is smaller than the sum of its proper divisors (30831210).

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

16721568 is a wasteful number, since it uses less digits than its factorization.

16721568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58077 (or 58066 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 16721568 is about 4089.2013890245. The cubic root of 16721568 is about 255.7166461206.

It can be divided in two parts, 1672 and 1568, that added together give a triangular number (3240 = T₈₀).

The spelling of 16721568 in words is "sixteen million, seven hundred twenty-one thousand, five hundred sixty-eight".