21724275 has 12 divisors (see below), whose sum is σ = 35917592. Its totient is φ = 11586240.

The previous prime is 21724271. The next prime is 21724303. The reversal of 21724275 is 57242712.

It is not a de Polignac number, because 21724275 - 2² = 21724271 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21724271) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 144754 + ... + 144903.

Almost surely, 2^21724275 is an apocalyptic number.

21724275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21724275 is a deficient number, since it is larger than the sum of its proper divisors (14193317).

21724275 is a wasteful number, since it uses less digits than its factorization.

21724275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289670 (or 289665 counting only the distinct ones).

The product of its digits is 7840, while the sum is 30.

The square root of 21724275 is about 4660.9307010510. The cubic root of 21724275 is about 279.0284140073.

Adding to 21724275 its reverse (57242712), we get a palindrome (78966987).

The spelling of 21724275 in words is "twenty-one million, seven hundred twenty-four thousand, two hundred seventy-five".