21244757 has 2 divisors, whose sum is σ = 21244758. Its totient is φ = 21244756.

The previous prime is 21244723. The next prime is 21244777. The reversal of 21244757 is 75744212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11062276 + 10182481 = 3326^2 + 3191^2 .

It is a cyclic number.

It is not a de Polignac number, because 21244757 - 2⁶ = 21244693 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21244777) 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, 10622378 + 10622379.

It is an arithmetic number, because the mean of its divisors is an integer number (10622379).

Almost surely, 2^21244757 is an apocalyptic number.

It is an amenable number.

21244757 is a deficient number, since it is larger than the sum of its proper divisors (1).

21244757 is an equidigital number, since it uses as much as digits as its factorization.

21244757 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15680, while the sum is 32.

The square root of 21244757 is about 4609.2035103692. The cubic root of 21244757 is about 276.9601310203.

Adding to 21244757 its reverse (75744212), we get a palindrome (96988969).

The spelling of 21244757 in words is "twenty-one million, two hundred forty-four thousand, seven hundred fifty-seven".