20163681 has 16 divisors (see below), whose sum is σ = 30184000. Its totient is φ = 13302144.

The previous prime is 20163643. The next prime is 20163697. The reversal of 20163681 is 18636102.

20163681 is a `hidden beast` number, since 20 + 1 + 636 + 8 + 1 = 666.

It is not a de Polignac number, because 20163681 - 2¹⁴ = 20147297 is a prime.

It is a super-2 number, since 2×20163681² = 813148062939522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20163641) 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, 1231 + ... + 6468.

It is an arithmetic number, because the mean of its divisors is an integer number (1886500).

Almost surely, 2^20163681 is an apocalyptic number.

It is an amenable number.

20163681 is a deficient number, since it is larger than the sum of its proper divisors (10020319).

20163681 is an equidigital number, since it uses as much as digits as its factorization.

20163681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7805 (or 7799 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 20163681 is about 4490.3987573488. The cubic root of 20163681 is about 272.1802483543.

Adding to 20163681 its reverse (18636102), we get a palindrome (38799783).

The spelling of 20163681 in words is "twenty million, one hundred sixty-three thousand, six hundred eighty-one".