21730272 has 24 divisors (see below), whose sum is σ = 57042216. Its totient is φ = 7243392.

The previous prime is 21730249. The next prime is 21730273. The reversal of 21730272 is 27203712.

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730273) 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, 113083 + ... + 113274.

It is an arithmetic number, because the mean of its divisors is an integer number (2376759).

Almost surely, 2^21730272 is an apocalyptic number.

It is an amenable number.

21730272 is an abundant number, since it is smaller than the sum of its proper divisors (35311944).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21730272 is a wasteful number, since it uses less digits than its factorization.

21730272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226370 (or 226362 counting only the distinct ones).

The product of its (nonzero) digits is 1176, while the sum is 24.

The square root of 21730272 is about 4661.5739831091. The cubic root of 21730272 is about 279.0540869691.

Adding to 21730272 its reverse (27203712), we get a palindrome (48933984).

The spelling of 21730272 in words is "twenty-one million, seven hundred thirty thousand, two hundred seventy-two".