21217159 has 2 divisors, whose sum is σ = 21217160. Its totient is φ = 21217158.

The previous prime is 21217151. The next prime is 21217187. The reversal of 21217159 is 95171212.

It is an a-pointer prime, because the next prime (21217187) can be obtained adding 21217159 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21217159 - 2³ = 21217151 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21217151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608579 + 10608580.

It is an arithmetic number, because the mean of its divisors is an integer number (10608580).

Almost surely, 2^21217159 is an apocalyptic number.

21217159 is a deficient number, since it is larger than the sum of its proper divisors (1).

21217159 is an equidigital number, since it uses as much as digits as its factorization.

21217159 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1260, while the sum is 28.

The square root of 21217159 is about 4606.2087447271. The cubic root of 21217159 is about 276.8401507059.

It can be divided in two parts, 21217 and 159, that multiplied together give a triangular number (3373503 = T₂₅₉₇).

The spelling of 21217159 in words is "twenty-one million, two hundred seventeen thousand, one hundred fifty-nine".