21617191 has 2 divisors, whose sum is σ = 21617192. Its totient is φ = 21617190.

The previous prime is 21617143. The next prime is 21617201. The reversal of 21617191 is 19171612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21617191 - 2¹⁷ = 21486119 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21617111) 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, 10808595 + 10808596.

It is an arithmetic number, because the mean of its divisors is an integer number (10808596).

Almost surely, 2^21617191 is an apocalyptic number.

21617191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21617191 is an equidigital number, since it uses as much as digits as its factorization.

21617191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 756, while the sum is 28.

The square root of 21617191 is about 4649.4291047396. The cubic root of 21617191 is about 278.5691933448.

The spelling of 21617191 in words is "twenty-one million, six hundred seventeen thousand, one hundred ninety-one".