20668681 has 16 divisors (see below), whose sum is σ = 23715648. Its totient is φ = 17841600.

The previous prime is 20668667. The next prime is 20668693. The reversal of 20668681 is 18686602.

It is a cyclic number.

It is not a de Polignac number, because 20668681 - 2⁷ = 20668553 is a prime.

It is a super-2 number, since 2×20668681² = 854388748559522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a self number, because there is not a number n which added to its sum of digits gives 20668681.

It is not an unprimeable number, because it can be changed into a prime (20668631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16911 + ... + 18091.

It is an arithmetic number, because the mean of its divisors is an integer number (1482228).

Almost surely, 2^20668681 is an apocalyptic number.

It is an amenable number.

20668681 is a deficient number, since it is larger than the sum of its proper divisors (3046967).

20668681 is a wasteful number, since it uses less digits than its factorization.

20668681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1272.

The product of its (nonzero) digits is 27648, while the sum is 37.

The square root of 20668681 is about 4546.2821073928. The cubic root of 20668681 is about 274.4337925910.

The spelling of 20668681 in words is "twenty million, six hundred sixty-eight thousand, six hundred eighty-one".