21281719 has 2 divisors, whose sum is σ = 21281720. Its totient is φ = 21281718.

The previous prime is 21281707. The next prime is 21281783. The reversal of 21281719 is 91718212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21281719 - 2⁹ = 21281207 is a prime.

It is a super-2 number, since 2×21281719² = 905823127189922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21281219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10640859 + 10640860.

It is an arithmetic number, because the mean of its divisors is an integer number (10640860).

Almost surely, 2^21281719 is an apocalyptic number.

21281719 is a deficient number, since it is larger than the sum of its proper divisors (1).

21281719 is an equidigital number, since it uses as much as digits as its factorization.

21281719 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 31.

The square root of 21281719 is about 4613.2113543604. The cubic root of 21281719 is about 277.1206579879.

The spelling of 21281719 in words is "twenty-one million, two hundred eighty-one thousand, seven hundred nineteen".