213612121 has 2 divisors, whose sum is σ = 213612122. Its totient is φ = 213612120.

The previous prime is 213612107. The next prime is 213612131. The reversal of 213612121 is 121216312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 163712025 + 49900096 = 12795^2 + 7064^2 .

It is a cyclic number.

It is not a de Polignac number, because 213612121 - 2¹¹ = 213610073 is a prime.

It is not a weakly prime, because it can be changed into another prime (213612131) 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, 106806060 + 106806061.

It is an arithmetic number, because the mean of its divisors is an integer number (106806061).

Almost surely, 2^213612121 is an apocalyptic number.

It is an amenable number.

213612121 is a deficient number, since it is larger than the sum of its proper divisors (1).

213612121 is an equidigital number, since it uses as much as digits as its factorization.

213612121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 144, while the sum is 19.

The square root of 213612121 is about 14615.4753942525. The cubic root of 213612121 is about 597.7808029866.

Adding to 213612121 its reverse (121216312), we get a palindrome (334828433).

The spelling of 213612121 in words is "two hundred thirteen million, six hundred twelve thousand, one hundred twenty-one".