18647536421 has 2 divisors, whose sum is σ = 18647536422. Its totient is φ = 18647536420.

The previous prime is 18647536393. The next prime is 18647536433. The reversal of 18647536421 is 12463574681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17979055396 + 668481025 = 134086^2 + 25855^2 .

It is a cyclic number.

It is not a de Polignac number, because 18647536421 - 2⁶ = 18647536357 is a prime.

It is a super-2 number, since 2×18647536421² (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 (18647536441) 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, 9323768210 + 9323768211.

It is an arithmetic number, because the mean of its divisors is an integer number (9323768211).

Almost surely, 2^18647536421 is an apocalyptic number.

It is an amenable number.

18647536421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18647536421 is an equidigital number, since it uses as much as digits as its factorization.

18647536421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 967680, while the sum is 47.

The spelling of 18647536421 in words is "eighteen billion, six hundred forty-seven million, five hundred thirty-six thousand, four hundred twenty-one".