163947681 has 6 divisors (see below), whose sum is σ = 236813330. Its totient is φ = 109298448.

The previous prime is 163947671. The next prime is 163947697. The reversal of 163947681 is 186749361.

It is a happy number.

163947681 is a `hidden beast` number, since 1 + 639 + 4 + 7 + 6 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 149817600 + 14130081 = 12240^2 + 3759^2 .

It is not a de Polignac number, because 163947681 - 2⁵ = 163947649 is a prime.

It is a super-2 number, since 2×163947681² = 53757684210555522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (163947661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9108196 + ... + 9108213.

Almost surely, 2^163947681 is an apocalyptic number.

It is an amenable number.

163947681 is a deficient number, since it is larger than the sum of its proper divisors (72865649).

163947681 is a wasteful number, since it uses less digits than its factorization.

163947681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18216415 (or 18216412 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 163947681 is about 12804.2055981619. The cubic root of 163947681 is about 547.3121542357.

The spelling of 163947681 in words is "one hundred sixty-three million, nine hundred forty-seven thousand, six hundred eighty-one".