165121213 has 2 divisors, whose sum is σ = 165121214. Its totient is φ = 165121212.

The previous prime is 165121211. The next prime is 165121237. The reversal of 165121213 is 312121561.

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., 89813529 + 75307684 = 9477^2 + 8678^2 .

It is a cyclic number.

It is not a de Polignac number, because 165121213 - 2¹ = 165121211 is a prime.

Together with 165121211, 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 (165121211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82560606 + 82560607.

It is an arithmetic number, because the mean of its divisors is an integer number (82560607).

Almost surely, 2^165121213 is an apocalyptic number.

It is an amenable number.

165121213 is a deficient number, since it is larger than the sum of its proper divisors (1).

165121213 is an equidigital number, since it uses as much as digits as its factorization.

165121213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 360, while the sum is 22.

The square root of 165121213 is about 12849.9499220814. The cubic root of 165121213 is about 548.6149314297.

Adding to 165121213 its reverse (312121561), we get a palindrome (477242774).

It can be divided in two parts, 1651212 and 13, that added together give a square (1651225 = 1285²).

The spelling of 165121213 in words is "one hundred sixty-five million, one hundred twenty-one thousand, two hundred thirteen".