20857857 has 8 divisors (see below), whose sum is σ = 28282080. Its totient is φ = 13669440.

The previous prime is 20857843. The next prime is 20857867. The reversal of 20857857 is 75875802.

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 20857857 - 2⁷ = 20857729 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20857867) 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, 58744 + ... + 59097.

It is an arithmetic number, because the mean of its divisors is an integer number (3535260).

Almost surely, 2^20857857 is an apocalyptic number.

It is an amenable number.

20857857 is a deficient number, since it is larger than the sum of its proper divisors (7424223).

20857857 is a wasteful number, since it uses less digits than its factorization.

20857857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117903.

The product of its (nonzero) digits is 156800, while the sum is 42.

The square root of 20857857 is about 4567.0402888523. The cubic root of 20857857 is about 275.2685288892.

The spelling of 20857857 in words is "twenty million, eight hundred fifty-seven thousand, eight hundred fifty-seven".