221888509 has 2 divisors, whose sum is σ = 221888510. Its totient is φ = 221888508.

The previous prime is 221888507. The next prime is 221888549. The reversal of 221888509 is 905888122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 220611609 + 1276900 = 14853^2 + 1130^2 .

It is a cyclic number.

It is not a de Polignac number, because 221888509 - 2¹ = 221888507 is a prime.

Together with 221888507, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221888507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110944254 + 110944255.

It is an arithmetic number, because the mean of its divisors is an integer number (110944255).

Almost surely, 2^221888509 is an apocalyptic number.

It is an amenable number.

221888509 is a deficient number, since it is larger than the sum of its proper divisors (1).

221888509 is an equidigital number, since it uses as much as digits as its factorization.

221888509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 92160, while the sum is 43.

The square root of 221888509 is about 14895.9225629029. The cubic root of 221888509 is about 605.4035137945.

The spelling of 221888509 in words is "two hundred twenty-one million, eight hundred eighty-eight thousand, five hundred nine".