20728687 has 8 divisors (see below), whose sum is σ = 23828256. Its totient is φ = 17663712.

The previous prime is 20728637. The next prime is 20728691. The reversal of 20728687 is 78682702.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20728687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20728637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7348 + ... + 9769.

It is an arithmetic number, because the mean of its divisors is an integer number (2978532).

Almost surely, 2^20728687 is an apocalyptic number.

20728687 is a deficient number, since it is larger than the sum of its proper divisors (3099569).

20728687 is a wasteful number, since it uses less digits than its factorization.

20728687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17297.

The product of its (nonzero) digits is 75264, while the sum is 40.

The square root of 20728687 is about 4552.8767828704. The cubic root of 20728687 is about 274.6991177516.

The spelling of 20728687 in words is "twenty million, seven hundred twenty-eight thousand, six hundred eighty-seven".