21501755630161 has 2 divisors, whose sum is σ = 21501755630162. Its totient is φ = 21501755630160.

The previous prime is 21501755630119. The next prime is 21501755630209. The reversal of 21501755630161 is 16103655710512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20494462380561 + 1007293249600 = 4527081^2 + 1003640^2 .

It is a cyclic number.

It is not a de Polignac number, because 21501755630161 - 2³³ = 21493165695569 is a prime.

It is not a weakly prime, because it can be changed into another prime (21501755610161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750877815080 + 10750877815081.

It is an arithmetic number, because the mean of its divisors is an integer number (10750877815081).

Almost surely, 2^{21501755630161} is an apocalyptic number.

It is an amenable number.

21501755630161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21501755630161 is an equidigital number, since it uses as much as digits as its factorization.

21501755630161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 189000, while the sum is 43.

The spelling of 21501755630161 in words is "twenty-one trillion, five hundred one billion, seven hundred fifty-five million, six hundred thirty thousand, one hundred sixty-one".