21109579 has 2 divisors, whose sum is σ = 21109580. Its totient is φ = 21109578.

The previous prime is 21109549. The next prime is 21109591. The reversal of 21109579 is 97590112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21109579 - 2¹¹ = 21107531 is a prime.

It is a super-2 number, since 2×21109579² = 891228651114482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21109549) 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, 10554789 + 10554790.

It is an arithmetic number, because the mean of its divisors is an integer number (10554790).

Almost surely, 2^21109579 is an apocalyptic number.

21109579 is a deficient number, since it is larger than the sum of its proper divisors (1).

21109579 is an equidigital number, since it uses as much as digits as its factorization.

21109579 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5670, while the sum is 34.

The square root of 21109579 is about 4594.5161878048. The cubic root of 21109579 is about 276.3714586398.

The spelling of 21109579 in words is "twenty-one million, one hundred nine thousand, five hundred seventy-nine".