How many seconds in monthly rate are equivalent to ±20ppm accuracy of time?

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If the accuracy of time is ±20ppm, then the monthly rate is 53.6 seconds.
The calculation formula is as follows:

• ±20 ｘ 10^-6 ｘ 60 sec. ｘ 60 min. ｘ 24 hrs. ｘ 31 days = ±53.6 sec./month

Supposed that the monthly rate should be within 1 minute, the accuracy of time must be equal or less than ±23.14ppm.