21043453 has 2 divisors, whose sum is σ = 21043454. Its totient is φ = 21043452.

The previous prime is 21043441. The next prime is 21043457. The reversal of 21043453 is 35434012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17665209 + 3378244 = 4203^2 + 1838^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21043453 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21043457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521726 + 10521727.

It is an arithmetic number, because the mean of its divisors is an integer number (10521727).

Almost surely, 2^21043453 is an apocalyptic number.

It is an amenable number.

21043453 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043453 is an equidigital number, since it uses as much as digits as its factorization.

21043453 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 21043453 is about 4587.3143559168. The cubic root of 21043453 is about 276.0825778601.

Adding to 21043453 its reverse (35434012), we get a palindrome (56477465).

The spelling of 21043453 in words is "twenty-one million, forty-three thousand, four hundred fifty-three".