21185458117 has 2 divisors, whose sum is σ = 21185458118. Its totient is φ = 21185458116.

The previous prime is 21185458103. The next prime is 21185458153. The reversal of 21185458117 is 71185458112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18124159876 + 3061298241 = 134626^2 + 55329^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21185458117 is a prime.

It is a super-2 number, since 2×21185458117² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21185458817) 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, 10592729058 + 10592729059.

It is an arithmetic number, because the mean of its divisors is an integer number (10592729059).

Almost surely, 2^21185458117 is an apocalyptic number.

It is an amenable number.

21185458117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21185458117 is an equidigital number, since it uses as much as digits as its factorization.

21185458117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 89600, while the sum is 43.

The spelling of 21185458117 in words is "twenty-one billion, one hundred eighty-five million, four hundred fifty-eight thousand, one hundred seventeen".