221205913 has 2 divisors, whose sum is σ = 221205914. Its totient is φ = 221205912.

The previous prime is 221205893. The next prime is 221205949. The reversal of 221205913 is 319502122.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 116920969 + 104284944 = 10813^2 + 10212^2 .

It is a cyclic number.

It is not a de Polignac number, because 221205913 - 2⁹ = 221205401 is a prime.

It is not a weakly prime, because it can be changed into another prime (221205983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110602956 + 110602957.

It is an arithmetic number, because the mean of its divisors is an integer number (110602957).

Almost surely, 2^221205913 is an apocalyptic number.

It is an amenable number.

221205913 is a deficient number, since it is larger than the sum of its proper divisors (1).

221205913 is an equidigital number, since it uses as much as digits as its factorization.

221205913 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 221205913 is about 14872.9927385177. The cubic root of 221205913 is about 604.7820748250.

The spelling of 221205913 in words is "two hundred twenty-one million, two hundred five thousand, nine hundred thirteen".