As a result of being exposed to the radiation released during the Chernobyl nuclear accident, the dose of iodine-131 in a person's body is 7.4 mCi (1 mCi = 1 × 10-3 Ci). Use the relationship rate = λN to calculate the number of atoms of iodine-131 this radioactivity corresponds. (The half-life of 131I is 8.1 d.)