21255134161 has 2 divisors, whose sum is σ = 21255134162. Its totient is φ = 21255134160.

The previous prime is 21255134107. The next prime is 21255134171. The reversal of 21255134161 is 16143155212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21012241936 + 242892225 = 144956^2 + 15585^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21255134161 is a prime.

It is not a weakly prime, because it can be changed into another prime (21255134101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627567080 + 10627567081.

It is an arithmetic number, because the mean of its divisors is an integer number (10627567081).

Almost surely, 2^21255134161 is an apocalyptic number.

It is an amenable number.

21255134161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255134161 is an equidigital number, since it uses as much as digits as its factorization.

21255134161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7200, while the sum is 31.

Adding to 21255134161 its reverse (16143155212), we get a palindrome (37398289373).

The spelling of 21255134161 in words is "twenty-one billion, two hundred fifty-five million, one hundred thirty-four thousand, one hundred sixty-one".