21011202161 has 2 divisors, whose sum is σ = 21011202162. Its totient is φ = 21011202160.

The previous prime is 21011202133. The next prime is 21011202209. The reversal of 21011202161 is 16120211012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14976864400 + 6034337761 = 122380^2 + 77681^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011202161 - 2³⁰ = 19937460337 is a prime.

It is a super-2 number, since 2×21011202161² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21011204161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505601080 + 10505601081.

It is an arithmetic number, because the mean of its divisors is an integer number (10505601081).

Almost surely, 2^21011202161 is an apocalyptic number.

It is an amenable number.

21011202161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011202161 is an equidigital number, since it uses as much as digits as its factorization.

21011202161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 17.

Adding to 21011202161 its reverse (16120211012), we get a palindrome (37131413173).

The spelling of 21011202161 in words is "twenty-one billion, eleven million, two hundred two thousand, one hundred sixty-one".