221279813 has 2 divisors, whose sum is σ = 221279814. Its totient is φ = 221279812.

The previous prime is 221279809. The next prime is 221279881. The reversal of 221279813 is 318972122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 192044164 + 29235649 = 13858^2 + 5407^2 .

It is a cyclic number.

It is not a de Polignac number, because 221279813 - 2² = 221279809 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (223279813) 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, 110639906 + 110639907.

It is an arithmetic number, because the mean of its divisors is an integer number (110639907).

Almost surely, 2^221279813 is an apocalyptic number.

It is an amenable number.

221279813 is a deficient number, since it is larger than the sum of its proper divisors (1).

221279813 is an equidigital number, since it uses as much as digits as its factorization.

221279813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 35.

The square root of 221279813 is about 14875.4768999182. The cubic root of 221279813 is about 604.8494154288.

The spelling of 221279813 in words is "two hundred twenty-one million, two hundred seventy-nine thousand, eight hundred thirteen".