221609172949 has 2 divisors, whose sum is σ = 221609172950. Its totient is φ = 221609172948.

The previous prime is 221609172853. The next prime is 221609173117. The reversal of 221609172949 is 949271906122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 196787170449 + 24822002500 = 443607^2 + 157550^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221609172949 is a prime.

It is a super-2 number, since 2×221609172949² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 221609172896 and 221609172905.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221609170949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110804586474 + 110804586475.

It is an arithmetic number, because the mean of its divisors is an integer number (110804586475).

Almost surely, 2^221609172949 is an apocalyptic number.

It is an amenable number.

221609172949 is a deficient number, since it is larger than the sum of its proper divisors (1).

221609172949 is an equidigital number, since it uses as much as digits as its factorization.

221609172949 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 979776, while the sum is 52.

The spelling of 221609172949 in words is "two hundred twenty-one billion, six hundred nine million, one hundred seventy-two thousand, nine hundred forty-nine".