Why is there white on the glans?

This is smegma. Just as sebum is secreted from all parts of the skin, sebaceous glands of the foreskin also secrete sebum. Since the foreskin cannot be turned up when the foreskin is phimosis or foreskin is too long, the sebum accumulates in the air between the foreskin and the penis head, and urine also seeps into this gap and chemically reacts with the sebum to become smegma and produce a strange odor. The smegma accumulated for a long time will become a hard lump. In the penis foreskin and the penis head junction of the subcutaneous, distribution of certain sebaceous glands. These glands constantly secrete some pale yellow oily substances, and some of the dirt and contaminated urine under the skin off mixed, the longer the accumulation of thicker can be flaky and small pieces, and tightly adhere to the skin of this part. If you don't bathe regularly or if you don't develop the habit of washing your lower body, this area will not be washed frequently, and the foreskin will accumulate thicker and stick to the skin tightly. The simple way to prevent this is to bathe regularly.