221601689 has 2 divisors, whose sum is σ = 221601690. Its totient is φ = 221601688.

The previous prime is 221601649. The next prime is 221601691. The reversal of 221601689 is 986106122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 220374025 + 1227664 = 14845^2 + 1108^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221601689 is a prime.

Together with 221601691, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221601649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110800844 + 110800845.

It is an arithmetic number, because the mean of its divisors is an integer number (110800845).

Almost surely, 2^221601689 is an apocalyptic number.

It is an amenable number.

221601689 is a deficient number, since it is larger than the sum of its proper divisors (1).

221601689 is an equidigital number, since it uses as much as digits as its factorization.

221601689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 221601689 is about 14886.2919828949. The cubic root of 221601689 is about 605.1425468361.

The spelling of 221601689 in words is "two hundred twenty-one million, six hundred one thousand, six hundred eighty-nine".