221728101 has 16 divisors (see below), whose sum is σ = 342632448. Its totient is φ = 124916400.

The previous prime is 221728099. The next prime is 221728121. The reversal of 221728101 is 101827122.

It is not a de Polignac number, because 221728101 - 2¹ = 221728099 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221728121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72865 + ... + 75846.

It is an arithmetic number, because the mean of its divisors is an integer number (21414528).

Almost surely, 2^221728101 is an apocalyptic number.

221728101 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

221728101 is a deficient number, since it is larger than the sum of its proper divisors (120904347).

221728101 is a wasteful number, since it uses less digits than its factorization.

221728101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148792.

The product of its (nonzero) digits is 448, while the sum is 24.

The square root of 221728101 is about 14890.5372972234. The cubic root of 221728101 is about 605.2575921962.

The spelling of 221728101 in words is "two hundred twenty-one million, seven hundred twenty-eight thousand, one hundred one".