21316859 has 2 divisors, whose sum is σ = 21316860. Its totient is φ = 21316858.

The previous prime is 21316849. The next prime is 21316891. The reversal of 21316859 is 95861312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21316859 - 2¹² = 21312763 is a prime.

It is a super-3 number, since 3×21316859³ (a number of 23 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21316819) 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, 10658429 + 10658430.

It is an arithmetic number, because the mean of its divisors is an integer number (10658430).

Almost surely, 2^21316859 is an apocalyptic number.

21316859 is a deficient number, since it is larger than the sum of its proper divisors (1).

21316859 is an equidigital number, since it uses as much as digits as its factorization.

21316859 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 35.

The square root of 21316859 is about 4617.0184101864. The cubic root of 21316859 is about 277.2730997006.

The spelling of 21316859 in words is "twenty-one million, three hundred sixteen thousand, eight hundred fifty-nine".