216827128609 has 135 divisors (see below), whose sum is σ = 297888123033. Its totient is φ = 157709051136.

The previous prime is 216827128561. The next prime is 216827128633. The reversal of 216827128609 is 906821728612.

The square root of 216827128609 is 465647.

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

It can be written as a sum of positive squares in 4 ways, for example, as 1957797009 + 214869331600 = 44247^2 + 463540^2 .

It is not a de Polignac number, because 216827128609 - 2¹⁷ = 216826997537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216827128709) by changing a digit.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 5042491342 + ... + 5042491384.

Almost surely, 2^216827128609 is an apocalyptic number.

216827128609 is the 465647-th square number.

216827128609 is the 232824-th centered octagonal number.

It is an amenable number.

216827128609 is a deficient number, since it is larger than the sum of its proper divisors (81060994424).

216827128609 is an frugal number, since it uses more digits than its factorization.

216827128609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174 (or 80 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 52.

The spelling of 216827128609 in words is "two hundred sixteen billion, eight hundred twenty-seven million, one hundred twenty-eight thousand, six hundred nine".