21724035 has 16 divisors (see below), whose sum is σ = 34853280. Its totient is φ = 11554560.

The previous prime is 21724019. The next prime is 21724037. The reversal of 21724035 is 53042712.

It is not a de Polignac number, because 21724035 - 2⁴ = 21724019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21723996 and 21724014.

It is not an unprimeable number, because it can be changed into a prime (21724037) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4365 + ... + 7905.

It is an arithmetic number, because the mean of its divisors is an integer number (2178330).

Almost surely, 2^21724035 is an apocalyptic number.

21724035 is a deficient number, since it is larger than the sum of its proper divisors (13129245).

21724035 is a wasteful number, since it uses less digits than its factorization.

21724035 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3958.

The product of its (nonzero) digits is 1680, while the sum is 24.

The square root of 21724035 is about 4660.9049550490. The cubic root of 21724035 is about 279.0273864768.

Adding to 21724035 its reverse (53042712), we get a palindrome (74766747).

The spelling of 21724035 in words is "twenty-one million, seven hundred twenty-four thousand, thirty-five".