21232018165481 has 2 divisors, whose sum is σ = 21232018165482. Its totient is φ = 21232018165480.

The previous prime is 21232018165417. The next prime is 21232018165507. The reversal of 21232018165481 is 18456181023212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20065382713600 + 1166635451881 = 4479440^2 + 1080109^2 .

It is a cyclic number.

It is not a de Polignac number, because 21232018165481 - 2⁶ = 21232018165417 is a prime.

It is a super-2 number, since 2×21232018165481² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21232018165781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10616009082740 + 10616009082741.

It is an arithmetic number, because the mean of its divisors is an integer number (10616009082741).

Almost surely, 2^{21232018165481} is an apocalyptic number.

It is an amenable number.

21232018165481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21232018165481 is an equidigital number, since it uses as much as digits as its factorization.

21232018165481 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 184320, while the sum is 44.

Adding to 21232018165481 its reverse (18456181023212), we get a palindrome (39688199188693).

The spelling of 21232018165481 in words is "twenty-one trillion, two hundred thirty-two billion, eighteen million, one hundred sixty-five thousand, four hundred eighty-one".