21040743 has 4 divisors (see below), whose sum is σ = 28054328. Its totient is φ = 14027160.

The previous prime is 21040741. The next prime is 21040759. The reversal of 21040743 is 34704012.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21040743 - 2¹ = 21040741 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 (21040741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3506788 + ... + 3506793.

It is an arithmetic number, because the mean of its divisors is an integer number (7013582).

Almost surely, 2^21040743 is an apocalyptic number.

21040743 is a deficient number, since it is larger than the sum of its proper divisors (7013585).

21040743 is an equidigital number, since it uses as much as digits as its factorization.

21040743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7013584.

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 21040743 is about 4587.0189666057. The cubic root of 21040743 is about 276.0707259411.

Adding to 21040743 its reverse (34704012), we get a palindrome (55744755).

The spelling of 21040743 in words is "twenty-one million, forty thousand, seven hundred forty-three".