213771661 has 2 divisors, whose sum is σ = 213771662. Its totient is φ = 213771660.

The previous prime is 213771653. The next prime is 213771697. The reversal of 213771661 is 166177312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 117614025 + 96157636 = 10845^2 + 9806^2 .

It is a cyclic number.

It is not a de Polignac number, because 213771661 - 2³ = 213771653 is a prime.

It is a super-3 number, since 3×213771661³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213771611) 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, 106885830 + 106885831.

It is an arithmetic number, because the mean of its divisors is an integer number (106885831).

Almost surely, 2^213771661 is an apocalyptic number.

It is an amenable number.

213771661 is a deficient number, since it is larger than the sum of its proper divisors (1).

213771661 is an equidigital number, since it uses as much as digits as its factorization.

213771661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10584, while the sum is 34.

The square root of 213771661 is about 14620.9322890163. The cubic root of 213771661 is about 597.9295870159.

The spelling of 213771661 in words is "two hundred thirteen million, seven hundred seventy-one thousand, six hundred sixty-one".