16388660020681 has 9 divisors (see below), whose sum is σ = 17746357483431. Its totient is φ = 15127945285752.

The previous prime is 16388660020673. The next prime is 16388660020721. The reversal of 16388660020681 is 18602006688361.

The square root of 16388660020681 is 4048291.

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., 2424357991225 + 13964302029456 = 1557035^2 + 3736884^2 .

It is not a de Polignac number, because 16388660020681 - 2³ = 16388660020673 is a prime.

It is a super-2 number, since 2×16388660020681² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16388660020651) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 52472080 + ... + 52783486.

It is an arithmetic number, because the mean of its divisors is an integer number (1971817498159).

Almost surely, 2^{16388660020681} is an apocalyptic number.

16388660020681 is the 4048291-st square number.

16388660020681 is the 2024146-th centered octagonal number.

It is an amenable number.

16388660020681 is a deficient number, since it is larger than the sum of its proper divisors (1357697462750).

16388660020681 is an frugal number, since it uses more digits than its factorization.

16388660020681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 622840 (or 311420 counting only the distinct ones).

The product of its (nonzero) digits is 3981312, while the sum is 55.

The spelling of 16388660020681 in words is "sixteen trillion, three hundred eighty-eight billion, six hundred sixty million, twenty thousand, six hundred eighty-one".