Problem:

When downloading Contacts from the Manager Portal in Everbridge Suite (Contacts > Contact List > Download), External IDs show as exponential numbers in the downloaded CSV file. This is true for both Active and Deleted Contacts. For example, 123456789123456789 shows as 1.23457E+17.

When clicking on the cell contents, the number shows as rounded up. For example, 1.23457E+17 shows as 123456789123456000.

Root Cause:

Microsoft Excel converts numeric values that exceed 15 digits to exponential numeric format.

Solution:

If you know what the External ID should be:

1. Open the downloaded file
2. Right-click on the target cell
3. Click on Format Cells
4. On the Number tab select Text
5. Click OK
6. Type the full External ID into the field
7. Optionally choose Ignore Error

In most cases, you will not know what the External ID should be. In these cases, follow the steps below:

1. Start MS Excel
2. Click File > Open > {name of your downloaded file} (This will open an import wizard box. NOTE: Do NOT open the file directly by clicking on it. If you do, the import wizard box will not open automatically.)
3. Choose Delimited
4. Next
5. Select the Comma delimiter (This selection presents the columns most clearly)
6. Next
7. Select the column which contains > 15 digits of numbers
8. Select Text (Do this after selecting the column so that only the format of this column is modified)
9. Select Finish. 

Below are some helpful links that explain the above issues and resolution:

https://answers.microsoft.com/en-us/msoffice/forum/msoffice_excel-mso_winother-mso_2010/excel-auto-roundoff-long-numbers-in-the-csv-file/da7d0929-4b2a-45a3-9187-cc4b9211a523
https://docs.microsoft.com/en-us/office/troubleshoot/excel/long-numbers-incorrectly-in-excel