21728230 has 8 divisors (see below), whose sum is σ = 39110832. Its totient is φ = 8691288.

The previous prime is 21728197. The next prime is 21728233. The reversal of 21728230 is 3282712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21728195 and 21728204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21728233) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1086402 + ... + 1086421.

It is an arithmetic number, because the mean of its divisors is an integer number (4888854).

Almost surely, 2^21728230 is an apocalyptic number.

21728230 is a deficient number, since it is larger than the sum of its proper divisors (17382602).

21728230 is a wasteful number, since it uses less digits than its factorization.

21728230 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2172830.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21728230 is about 4661.3549532298. The cubic root of 21728230 is about 279.0453457640.

The spelling of 21728230 in words is "twenty-one million, seven hundred twenty-eight thousand, two hundred thirty".