163640726981 has 16 divisors (see below), whose sum is σ = 170224104960. Its totient is φ = 157122443520.

The previous prime is 163640726969. The next prime is 163640727007. The reversal of 163640726981 is 189627046361.

It is a cyclic number.

It is not a de Polignac number, because 163640726981 - 2³⁰ = 162566985157 is a prime.

It is a super-2 number, since 2×163640726981² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163640728981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3884276 + ... + 3926178.

It is an arithmetic number, because the mean of its divisors is an integer number (10639006560).

Almost surely, 2^163640726981 is an apocalyptic number.

It is an amenable number.

163640726981 is a deficient number, since it is larger than the sum of its proper divisors (6583377979).

163640726981 is a wasteful number, since it uses less digits than its factorization.

163640726981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42676.

The product of its (nonzero) digits is 2612736, while the sum is 53.

The spelling of 163640726981 in words is "one hundred sixty-three billion, six hundred forty million, seven hundred twenty-six thousand, nine hundred eighty-one".