WASHINGTON (AP) _ The government's total indebtedness, usually called the national debt and representing an accumulation of decades of deficit spending, had reached $1,950,293,000,000 by the end of 1985, according to Treasury Department calculations.

This debt of nearly $2 trillion included $1.4 trillion, or 73 percent, owed to the public. The remaining 27 percent was owned by the federal government itself, invested in various government trust funds such as Social Security.

The debt held by the public includes $154.7 billion (8 percent of the total) held by individuals. Of this, $79.8 billion (4 percent) is invested in savings bonds.

The rest of the national debt is held by commercial banks, insurance companies, money market funds, corporations, state and local governments and foreign investors.

The amount held by foreigners totaled $209.8 billion (12 percent of the total) in September. This represented an increase of $50.1 billion since September 1984.