21161002251161 has 2 divisors, whose sum is σ = 21161002251162. Its totient is φ = 21161002251160.

The previous prime is 21161002251139. The next prime is 21161002251173. The reversal of 21161002251161 is 16115220016112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15875283984400 + 5285718266761 = 3984380^2 + 2299069^2 .

It is a cyclic number.

It is not a de Polignac number, because 21161002251161 - 2⁶ = 21161002251097 is a prime.

It is not a weakly prime, because it can be changed into another prime (21161002251061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10580501125580 + 10580501125581.

It is an arithmetic number, because the mean of its divisors is an integer number (10580501125581).

Almost surely, 2^{21161002251161} is an apocalyptic number.

It is an amenable number.

21161002251161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21161002251161 is an equidigital number, since it uses as much as digits as its factorization.

21161002251161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 29.

Adding to 21161002251161 its reverse (16115220016112), we get a palindrome (37276222267273).

The spelling of 21161002251161 in words is "twenty-one trillion, one hundred sixty-one billion, two million, two hundred fifty-one thousand, one hundred sixty-one".