16512820578409 has 27 divisors (see below), whose sum is σ = 16870953285687. Its totient is φ = 16162258128816.

The previous prime is 16512820578403. The next prime is 16512820578413. The reversal of 16512820578409 is 90487502821561.

The square root of 16512820578409 is 4063597.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 15020934219225 + 1491886359184 = 3875685^2 + 1221428^2 .

It is not a de Polignac number, because 16512820578409 - 2⁷ = 16512820578281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16512820578403) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 58349189182 + ... + 58349189464.

Almost surely, 2^{16512820578409} is an apocalyptic number.

16512820578409 is the 4063597-th square number.

16512820578409 is the 2031799-th centered octagonal number.

It is an amenable number.

16512820578409 is a deficient number, since it is larger than the sum of its proper divisors (358132707278).

16512820578409 is an frugal number, since it uses more digits than its factorization.

16512820578409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1078 (or 539 counting only the distinct ones).

The product of its (nonzero) digits is 9676800, while the sum is 58.

The spelling of 16512820578409 in words is "sixteen trillion, five hundred twelve billion, eight hundred twenty million, five hundred seventy-eight thousand, four hundred nine".