21788416881 has 189 divisors, whose sum is σ = 42366486729. Its totient is φ = 11159240400.

The previous prime is 21788416823. The next prime is 21788416889. The reversal of 21788416881 is 18861488712.

The square root of 21788416881 is 147609.

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

21788416881 is a `hidden beast` number, since 217 + 8 + 8 + 416 + 8 + 8 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (189).

It is not a de Polignac number, because 21788416881 - 2⁷ = 21788416753 is a prime.

It is a super-2 number, since 2×21788416881² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21788416889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 188 ways as a sum of consecutive naturals, for example, 306879076 + ... + 306879146.

Almost surely, 2^21788416881 is an apocalyptic number.

21788416881 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21788416881 is the 147609-th square number.

21788416881 is the 73805-th centered octagonal number.

It is an amenable number.

21788416881 is a deficient number, since it is larger than the sum of its proper divisors (20578069848).

21788416881 is an frugal number, since it uses more digits than its factorization.

21788416881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 92 counting only the distinct ones).

The product of its digits is 1376256, while the sum is 54.

The spelling of 21788416881 in words is "twenty-one billion, seven hundred eighty-eight million, four hundred sixteen thousand, eight hundred eighty-one".