21240535 has 8 divisors (see below), whose sum is σ = 25595856. Its totient is φ = 16920960.

The previous prime is 21240529. The next prime is 21240539. The reversal of 21240535 is 53504212.

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

It is not a de Polignac number, because 21240535 - 2¹¹ = 21238487 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240539) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7609 + ... + 10018.

It is an arithmetic number, because the mean of its divisors is an integer number (3199482).

Almost surely, 2^21240535 is an apocalyptic number.

21240535 is a deficient number, since it is larger than the sum of its proper divisors (4355321).

21240535 is a wasteful number, since it uses less digits than its factorization.

21240535 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17873.

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 21240535 is about 4608.7454909118. The cubic root of 21240535 is about 276.9417829145.

Adding to 21240535 its reverse (53504212), we get a palindrome (74744747).

The spelling of 21240535 in words is "twenty-one million, two hundred forty thousand, five hundred thirty-five".