21212021161 has 2 divisors, whose sum is σ = 21212021162. Its totient is φ = 21212021160.

The previous prime is 21212021143. The next prime is 21212021221. The reversal of 21212021161 is 16112021212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16914563136 + 4297458025 = 130056^2 + 65555^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212021161 - 2¹¹ = 21212019113 is a prime.

It is not a weakly prime, because it can be changed into another prime (21212021461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606010580 + 10606010581.

It is an arithmetic number, because the mean of its divisors is an integer number (10606010581).

Almost surely, 2^21212021161 is an apocalyptic number.

It is an amenable number.

21212021161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212021161 is an equidigital number, since it uses as much as digits as its factorization.

21212021161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 19.

Adding to 21212021161 its reverse (16112021212), we get a palindrome (37324042373).

The spelling of 21212021161 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, one hundred sixty-one".