21724797 has 8 divisors (see below), whose sum is σ = 29253600. Its totient is φ = 14339600.

The previous prime is 21724783. The next prime is 21724819. The reversal of 21724797 is 79742712.

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

It is a cyclic number.

It is not a de Polignac number, because 21724797 - 2¹¹ = 21722749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21724757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35547 + ... + 36152.

It is an arithmetic number, because the mean of its divisors is an integer number (3656700).

Almost surely, 2^21724797 is an apocalyptic number.

It is an amenable number.

21724797 is a deficient number, since it is larger than the sum of its proper divisors (7528803).

21724797 is a wasteful number, since it uses less digits than its factorization.

21724797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71803.

The product of its digits is 49392, while the sum is 39.

The square root of 21724797 is about 4660.9866981145. The cubic root of 21724797 is about 279.0306488600.

The spelling of 21724797 in words is "twenty-one million, seven hundred twenty-four thousand, seven hundred ninety-seven".