21523361 has 2 divisors, whose sum is σ = 21523362. Its totient is φ = 21523360.

The previous prime is 21523351. The next prime is 21523387. The reversal of 21523361 is 16332512.

21523361 = 3280² + 3281².

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10764961 + 10758400 = 3281^2 + 3280^2 .

It is a cyclic number.

It is not a de Polignac number, because 21523361 - 2¹⁰ = 21522337 is a prime.

It is a Chen prime.

It is a plaindrome in base 3 and base 9.

It is not a weakly prime, because it can be changed into another prime (21523351) 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 as a sum of consecutive naturals, namely, 10761680 + 10761681.

It is an arithmetic number, because the mean of its divisors is an integer number (10761681).

Almost surely, 2^21523361 is an apocalyptic number.

21523361 is the 3281-st centered square number.

It is an amenable number.

21523361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21523361 is an equidigital number, since it uses as much as digits as its factorization.

21523361 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 23.

The square root of 21523361 is about 4639.3276452521. The cubic root of 21523361 is about 278.1655630944.

Adding to 21523361 its reverse (16332512), we get a palindrome (37855873).

The spelling of 21523361 in words is "twenty-one million, five hundred twenty-three thousand, three hundred sixty-one".