21563273 has 2 divisors, whose sum is σ = 21563274. Its totient is φ = 21563272.

The previous prime is 21563257. The next prime is 21563303. The reversal of 21563273 is 37236512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21501769 + 61504 = 4637^2 + 248^2 .

It is a cyclic number.

It is not a de Polignac number, because 21563273 - 2⁴ = 21563257 is a prime.

It is not a weakly prime, because it can be changed into another prime (21563173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10781636 + 10781637.

It is an arithmetic number, because the mean of its divisors is an integer number (10781637).

Almost surely, 2^21563273 is an apocalyptic number.

It is an amenable number.

21563273 is a deficient number, since it is larger than the sum of its proper divisors (1).

21563273 is an equidigital number, since it uses as much as digits as its factorization.

21563273 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 29.

The square root of 21563273 is about 4643.6271383478. The cubic root of 21563273 is about 278.3373963654.

Adding to 21563273 its reverse (37236512), we get a palindrome (58799785).

The spelling of 21563273 in words is "twenty-one million, five hundred sixty-three thousand, two hundred seventy-three".