21159109 has 2 divisors, whose sum is σ = 21159110. Its totient is φ = 21159108.

The previous prime is 21159091. The next prime is 21159119. The reversal of 21159109 is 90195112.

Together with previous prime (21159091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20930625 + 228484 = 4575^2 + 478^2 .

It is a cyclic number.

It is not a de Polignac number, because 21159109 - 2¹³ = 21150917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21159119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10579554 + 10579555.

It is an arithmetic number, because the mean of its divisors is an integer number (10579555).

Almost surely, 2^21159109 is an apocalyptic number.

It is an amenable number.

21159109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21159109 is an equidigital number, since it uses as much as digits as its factorization.

21159109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 810, while the sum is 28.

The square root of 21159109 is about 4599.9031511544. The cubic root of 21159109 is about 276.5874425183.

The spelling of 21159109 in words is "twenty-one million, one hundred fifty-nine thousand, one hundred nine".