221538133 has 2 divisors, whose sum is σ = 221538134. Its totient is φ = 221538132.

The previous prime is 221538131. The next prime is 221538151. The reversal of 221538133 is 331835122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 154330929 + 67207204 = 12423^2 + 8198^2 .

It is a cyclic number.

It is not a de Polignac number, because 221538133 - 2¹ = 221538131 is a prime.

Together with 221538131, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221538131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110769066 + 110769067.

It is an arithmetic number, because the mean of its divisors is an integer number (110769067).

Almost surely, 2^221538133 is an apocalyptic number.

It is an amenable number.

221538133 is a deficient number, since it is larger than the sum of its proper divisors (1).

221538133 is an equidigital number, since it uses as much as digits as its factorization.

221538133 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 28.

The square root of 221538133 is about 14884.1571141936. The cubic root of 221538133 is about 605.0846890984.

The spelling of 221538133 in words is "two hundred twenty-one million, five hundred thirty-eight thousand, one hundred thirty-three".