Which Mongolian city had a 2021 population of 1,672,627?

Ulaanbaatar had a population of 1,672,627 in 2021, so it is the Mongolian city described in the question.

Ulaanbaatar is Mongolia’s capital and overwhelmingly its largest city. It sits in a valley along the Tuul River in north-central Mongolia, at an elevation of about 1,350 metres. The municipality is also the country’s political, educational, cultural, industrial, and transport hub, concentrating close to half of Mongolia’s population.

The city began in 1639 as a mobile Buddhist monastic centre and changed location many times before settling permanently at its modern site in 1778. It was known historically as Örgöö and Urga, among other names, and adopted the name Ulaanbaatar—“Red Hero”—in 1924 after Mongolia’s revolution.

A frequent mistake is treating Darkhan or Erdenet as the likely answer because both are important Mongolian cities. They are much smaller, while Ulaanbaatar’s rapid growth has been driven by rural-to-urban migration. The 2021 figure refers to the municipality, whose broad boundaries include dense urban districts and ger areas.