21040753 has 4 divisors (see below), whose sum is σ = 21609460. Its totient is φ = 20472048.

The previous prime is 21040741. The next prime is 21040759. The reversal of 21040753 is 35704012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18258529 + 2782224 = 4273^2 + 1668^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21040753 is a prime.

It is a super-3 number, since 3×21040753³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21040759) 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, 284298 + ... + 284371.

It is an arithmetic number, because the mean of its divisors is an integer number (5402365).

Almost surely, 2^21040753 is an apocalyptic number.

It is an amenable number.

21040753 is a deficient number, since it is larger than the sum of its proper divisors (568707).

21040753 is an equidigital number, since it uses as much as digits as its factorization.

21040753 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 568706.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21040753 is about 4587.0200566381. The cubic root of 21040753 is about 276.0707696770.

Adding to 21040753 its reverse (35704012), we get a palindrome (56744765).

The spelling of 21040753 in words is "twenty-one million, forty thousand, seven hundred fifty-three".