21240041 has 4 divisors (see below), whose sum is σ = 21370512. Its totient is φ = 21109572.

The previous prime is 21240001. The next prime is 21240049. The reversal of 21240041 is 14004212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21240041 is a prime.

It is a super-2 number, since 2×21240041² = 902278683363362, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21239998 and 21240025.

It is not an unprimeable number, because it can be changed into a prime (21240049) 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, 64991 + ... + 65316.

It is an arithmetic number, because the mean of its divisors is an integer number (5342628).

Almost surely, 2^21240041 is an apocalyptic number.

It is an amenable number.

21240041 is a deficient number, since it is larger than the sum of its proper divisors (130471).

21240041 is a wasteful number, since it uses less digits than its factorization.

21240041 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130470.

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21240041 is about 4608.6918968401. The cubic root of 21240041 is about 276.9396359143.

Adding to 21240041 its reverse (14004212), we get a palindrome (35244253).

The spelling of 21240041 in words is "twenty-one million, two hundred forty thousand, forty-one".