21728119 has 6 divisors (see below), whose sum is σ = 25275624. Its totient is φ = 18624060.

The previous prime is 21728111. The next prime is 21728129. The reversal of 21728119 is 91182712.

It is not a de Polignac number, because 21728119 - 2³ = 21728111 is a prime.

It is a super-2 number, since 2×21728119² = 944222310556322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21728111) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 221667 + ... + 221764.

It is an arithmetic number, because the mean of its divisors is an integer number (4212604).

Almost surely, 2^21728119 is an apocalyptic number.

21728119 is a deficient number, since it is larger than the sum of its proper divisors (3547505).

21728119 is an equidigital number, since it uses as much as digits as its factorization.

21728119 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 443445 (or 443438 counting only the distinct ones).

The product of its digits is 2016, while the sum is 31.

The square root of 21728119 is about 4661.3430468053. The cubic root of 21728119 is about 279.0448705897.

The spelling of 21728119 in words is "twenty-one million, seven hundred twenty-eight thousand, one hundred nineteen".