21281677 has 2 divisors, whose sum is σ = 21281678. Its totient is φ = 21281676.

The previous prime is 21281669. The next prime is 21281683. The reversal of 21281677 is 77618212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19483396 + 1798281 = 4414^2 + 1341^2 .

It is a cyclic number.

It is not a de Polignac number, because 21281677 - 2³ = 21281669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21281627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10640838 + 10640839.

It is an arithmetic number, because the mean of its divisors is an integer number (10640839).

Almost surely, 2^21281677 is an apocalyptic number.

It is an amenable number.

21281677 is a deficient number, since it is larger than the sum of its proper divisors (1).

21281677 is an equidigital number, since it uses as much as digits as its factorization.

21281677 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9408, while the sum is 34.

The square root of 21281677 is about 4613.2068022147. The cubic root of 21281677 is about 277.1204756863.

Adding to 21281677 its reverse (77618212), we get a palindrome (98899889).

The spelling of 21281677 in words is "twenty-one million, two hundred eighty-one thousand, six hundred seventy-seven".