Num2Text converts numbers into words inside Google Sheets™.

Functions:
=NUM2TEXT(A1) → Korean (e.g. 칠십칠만)
=NUM2TEXT(A1, "en") → English
=NUM2TEXT(A1, "ja") → Japanese
=NUM2TEXT(A1, "zh") → Chinese
=NUM2TEXT(A1, "es"|"fr"|"de") → Spanish, French, or German
=NUM2COMMA(A1) → 770,000

Supported languages: ko, en, ja, zh, es, fr, de

After install: Extensions → Num2Text → Help

Google Sheets™ is a trademark of Google LLC.