21436573 has 2 divisors, whose sum is σ = 21436574. Its totient is φ = 21436572.

The previous prime is 21436567. The next prime is 21436601. The reversal of 21436573 is 37563412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17665209 + 3771364 = 4203^2 + 1942^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21436573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21436873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10718286 + 10718287.

It is an arithmetic number, because the mean of its divisors is an integer number (10718287).

Almost surely, 2^21436573 is an apocalyptic number.

It is an amenable number.

21436573 is a deficient number, since it is larger than the sum of its proper divisors (1).

21436573 is an equidigital number, since it uses as much as digits as its factorization.

21436573 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 31.

The square root of 21436573 is about 4629.9646866904. The cubic root of 21436573 is about 277.7911798986.

Adding to 21436573 its reverse (37563412), we get a palindrome (58999985).

The spelling of 21436573 in words is "twenty-one million, four hundred thirty-six thousand, five hundred seventy-three".