20718691 has 8 divisors (see below), whose sum is σ = 23710464. Its totient is φ = 17734920.

The previous prime is 20718689. The next prime is 20718697. The reversal of 20718691 is 19681702.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20718691 - 2¹ = 20718689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20718697) 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 7 ways as a sum of consecutive naturals, for example, 5376 + ... + 8386.

It is an arithmetic number, because the mean of its divisors is an integer number (2963808).

Almost surely, 2^20718691 is an apocalyptic number.

20718691 is a deficient number, since it is larger than the sum of its proper divisors (2991773).

20718691 is an equidigital number, since it uses as much as digits as its factorization.

20718691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4001.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 20718691 is about 4551.7788830302. The cubic root of 20718691 is about 274.6549545767.

The spelling of 20718691 in words is "twenty million, seven hundred eighteen thousand, six hundred ninety-one".