21161002251061 has 2 divisors, whose sum is σ = 21161002251062. Its totient is φ = 21161002251060.

The previous prime is 21161002251019. The next prime is 21161002251097. The reversal of 21161002251061 is 16015220016112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13632119308900 + 7528882942161 = 3692170^2 + 2743881^2 .

It is a cyclic number.

It is not a de Polignac number, because 21161002251061 - 2¹⁷ = 21161002119989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21161002251161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10580501125530 + 10580501125531.

It is an arithmetic number, because the mean of its divisors is an integer number (10580501125531).

Almost surely, 2^{21161002251061} is an apocalyptic number.

It is an amenable number.

21161002251061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21161002251061 is an equidigital number, since it uses as much as digits as its factorization.

21161002251061 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 28.

Adding to 21161002251061 its reverse (16015220016112), we get a palindrome (37176222267173).

The spelling of 21161002251061 in words is "twenty-one trillion, one hundred sixty-one billion, two million, two hundred fifty-one thousand, sixty-one".