21719459 has 2 divisors, whose sum is σ = 21719460. Its totient is φ = 21719458.

The previous prime is 21719443. The next prime is 21719461. The reversal of 21719459 is 95491712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21719459 - 2⁴ = 21719443 is a prime.

It is a Sophie Germain prime.

Together with 21719461, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21719419) 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, 10859729 + 10859730.

It is an arithmetic number, because the mean of its divisors is an integer number (10859730).

Almost surely, 2^21719459 is an apocalyptic number.

21719459 is a deficient number, since it is larger than the sum of its proper divisors (1).

21719459 is an equidigital number, since it uses as much as digits as its factorization.

21719459 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22680, while the sum is 38.

The square root of 21719459 is about 4660.4140374005. The cubic root of 21719459 is about 279.0077934472.

The spelling of 21719459 in words is "twenty-one million, seven hundred nineteen thousand, four hundred fifty-nine".