168664365981 has 48 divisors (see below), whose sum is σ = 259282623600. Its totient is φ = 105285795840.

The previous prime is 168664365973. The next prime is 168664366033. The reversal of 168664365981 is 189563466861.

168664365981 is a `hidden beast` number, since 1 + 6 + 8 + 6 + 6 + 4 + 36 + 598 + 1 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 21776904900 + 146887461081 = 147570^2 + 383259^2 .

It is not a de Polignac number, because 168664365981 - 2³ = 168664365973 is a prime.

It is a super-2 number, since 2×168664365981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168664365911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 57114801 + ... + 57117753.

It is an arithmetic number, because the mean of its divisors is an integer number (5401721325).

Almost surely, 2^168664365981 is an apocalyptic number.

It is an amenable number.

168664365981 is a deficient number, since it is larger than the sum of its proper divisors (90618257619).

168664365981 is a wasteful number, since it uses less digits than its factorization.

168664365981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4766 (or 4763 counting only the distinct ones).

The product of its digits is 44789760, while the sum is 63.

The spelling of 168664365981 in words is "one hundred sixty-eight billion, six hundred sixty-four million, three hundred sixty-five thousand, nine hundred eighty-one".