163687681621 has 2 divisors, whose sum is σ = 163687681622. Its totient is φ = 163687681620.

The previous prime is 163687681571. The next prime is 163687681649. The reversal of 163687681621 is 126186786361.

163687681621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 152694159121 + 10993522500 = 390761^2 + 104850^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-163687681621 is a prime.

It is a super-2 number, since 2×163687681621² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (163687681121) 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, 81843840810 + 81843840811.

It is an arithmetic number, because the mean of its divisors is an integer number (81843840811).

Almost surely, 2^163687681621 is an apocalyptic number.

It is an amenable number.

163687681621 is a deficient number, since it is larger than the sum of its proper divisors (1).

163687681621 is an equidigital number, since it uses as much as digits as its factorization.

163687681621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3483648, while the sum is 55.

The spelling of 163687681621 in words is "one hundred sixty-three billion, six hundred eighty-seven million, six hundred eighty-one thousand, six hundred twenty-one".