Disable Scientific Notation in CONCAT

Hi again
I’m trying to use one of my excel sheets in libre and have come across an issue where the CONCAT function changes my number to scientific notation.
I’m using this to combine lots of data to a string I can past in other software, to do this I need to use a UNIX time code which is 19 numbers long but no matter what I do it always reduces it to be 1.234E+018 which doesn’t work in the input field any help would be appreciated.

Spreadsheets can not deal with 19 digits. The internal data type is Double-precision floating-point format - Wikipedia
What is a UNIX time code?

I was afraid of that, it did work in Excel though maybe I’ll have to run a VM just for this.
UNIX time is the number of seconds that have elapsed since January 1, 1970 but what I’m using it for uses nanosecond precision.

Import the digits as text and cut off micro/nano digits. Then convert to number again.

The issue is with the CONCAT function as I need to combine several bits of text and numbers together and whenever I use that it changes to Scientific Notation even if I have the cell its getting data from formatted to display all numbers, example of my full CONCAT expected output “Cost,tarrif=Peak Grid_Consumption_Cost=0.01967944 1735651846821576348”.
I think I have a way around it just going to take a lot of editing, I’ll lose the full precision and just add some 0’s to the end via an extra CONCAT field. Thanks

Meaning that your data wasn’t a number in Excel - because Excel also can’t deal with 19 digit numbers.

Without a sample data, it’s difficult to advise anything specific.

May be, Excel treats long sequences of digits as string instead of rounding the number.