18721835166869 has 2 divisors, whose sum is σ = 18721835166870. Its totient is φ = 18721835166868.

The previous prime is 18721835166857. The next prime is 18721835166929. The reversal of 18721835166869 is 96866153812781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12529511487025 + 6192323679844 = 3539705^2 + 2488438^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18721835166869 is a prime.

It is a super-2 number, since 2×18721835166869² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (48721835166869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9360917583434 + 9360917583435.

It is an arithmetic number, because the mean of its divisors is an integer number (9360917583435).

Almost surely, 2^{18721835166869} is an apocalyptic number.

It is an amenable number.

18721835166869 is a deficient number, since it is larger than the sum of its proper divisors (1).

18721835166869 is an equidigital number, since it uses as much as digits as its factorization.

18721835166869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209018880, while the sum is 71.

The spelling of 18721835166869 in words is "eighteen trillion, seven hundred twenty-one billion, eight hundred thirty-five million, one hundred sixty-six thousand, eight hundred sixty-nine".