20668747 has 4 divisors (see below), whose sum is σ = 22547736. Its totient is φ = 18789760.

The previous prime is 20668733. The next prime is 20668759. The reversal of 20668747 is 74786602.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-20668747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20668727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 939478 + ... + 939499.

It is an arithmetic number, because the mean of its divisors is an integer number (5636934).

Almost surely, 2^20668747 is an apocalyptic number.

20668747 is a deficient number, since it is larger than the sum of its proper divisors (1878989).

20668747 is a wasteful number, since it uses less digits than its factorization.

20668747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1878988.

The product of its (nonzero) digits is 112896, while the sum is 40.

The square root of 20668747 is about 4546.2893660655. The cubic root of 20668747 is about 274.4340847014.

The spelling of 20668747 in words is "twenty million, six hundred sixty-eight thousand, seven hundred forty-seven".