21581488073 has 2 divisors, whose sum is σ = 21581488074. Its totient is φ = 21581488072.

The previous prime is 21581488069. The next prime is 21581488081. The reversal of 21581488073 is 37088418512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17022942784 + 4558545289 = 130472^2 + 67517^2 .

It is a cyclic number.

It is not a de Polignac number, because 21581488073 - 2² = 21581488069 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21581488013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10790744036 + 10790744037.

It is an arithmetic number, because the mean of its divisors is an integer number (10790744037).

Almost surely, 2^21581488073 is an apocalyptic number.

It is an amenable number.

21581488073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21581488073 is an equidigital number, since it uses as much as digits as its factorization.

21581488073 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 430080, while the sum is 47.

The spelling of 21581488073 in words is "twenty-one billion, five hundred eighty-one million, four hundred eighty-eight thousand, seventy-three".