21757873 has 2 divisors, whose sum is σ = 21757874. Its totient is φ = 21757872.

The previous prime is 21757849. The next prime is 21757951. The reversal of 21757873 is 37875712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14961424 + 6796449 = 3868^2 + 2607^2 .

It is a cyclic number.

It is not a de Polignac number, because 21757873 - 2⁹ = 21757361 is a prime.

It is not a weakly prime, because it can be changed into another prime (21752873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10878936 + 10878937.

It is an arithmetic number, because the mean of its divisors is an integer number (10878937).

Almost surely, 2^21757873 is an apocalyptic number.

It is an amenable number.

21757873 is a deficient number, since it is larger than the sum of its proper divisors (1).

21757873 is an equidigital number, since it uses as much as digits as its factorization.

21757873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82320, while the sum is 40.

The square root of 21757873 is about 4664.5335243730. The cubic root of 21757873 is about 279.1721850943.

The spelling of 21757873 in words is "twenty-one million, seven hundred fifty-seven thousand, eight hundred seventy-three".