221205137 has 2 divisors, whose sum is σ = 221205138. Its totient is φ = 221205136.

The previous prime is 221205121. The next prime is 221205143. The reversal of 221205137 is 731502122.

It is a happy number.

221205137 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 220492801 + 712336 = 14849^2 + 844^2 .

It is a cyclic number.

It is not a de Polignac number, because 221205137 - 2⁴ = 221205121 is a prime.

It is not a weakly prime, because it can be changed into another prime (221205637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110602568 + 110602569.

It is an arithmetic number, because the mean of its divisors is an integer number (110602569).

Almost surely, 2^221205137 is an apocalyptic number.

It is an amenable number.

221205137 is a deficient number, since it is larger than the sum of its proper divisors (1).

221205137 is an equidigital number, since it uses as much as digits as its factorization.

221205137 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 221205137 is about 14872.9666509409. The cubic root of 221205137 is about 604.7813676236.

Adding to 221205137 its reverse (731502122), we get a palindrome (952707259).

The spelling of 221205137 in words is "two hundred twenty-one million, two hundred five thousand, one hundred thirty-seven".