In humans, there are 46 chromosomes in a stomach cell. The stomach, like most of the body, is composed of somatic cells, so the number of chromosomes in a stomach cell is equivalent to an organism's diploid number.
Somatic cells are cells that make up the body of the organism; most cells in the body are somatic cells. Somatic cells are diploid, which means they contain two complementary sets of chromosomes, one inherited from each parent. The diploid number is the number of chromosomes contained in a diploid cell for a given organism. Chromosomes are the physical structures in which an organism's genes are located. Different organisms contain different numbers of chromosomes; for example, the stomach cell of a domestic dog contains 78 chromosomes. Chromosome number isn't related to the complexity of an organism.