221540009 has 2 divisors, whose sum is σ = 221540010. Its totient is φ = 221540008.

The previous prime is 221539963. The next prime is 221540017. The reversal of 221540009 is 900045122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 135792409 + 85747600 = 11653^2 + 9260^2 .

It is a cyclic number.

It is not a de Polignac number, because 221540009 - 2¹² = 221535913 is a prime.

It is not a weakly prime, because it can be changed into another prime (221540089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110770004 + 110770005.

It is an arithmetic number, because the mean of its divisors is an integer number (110770005).

Almost surely, 2^221540009 is an apocalyptic number.

It is an amenable number.

221540009 is a deficient number, since it is larger than the sum of its proper divisors (1).

221540009 is an equidigital number, since it uses as much as digits as its factorization.

221540009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 221540009 is about 14884.2201340883. The cubic root of 221540009 is about 605.0863970597.

It can be divided in two parts, 2215 and 40009, that added together give a palindrome (42224).

The spelling of 221540009 in words is "two hundred twenty-one million, five hundred forty thousand, nine".