20857557 has 8 divisors (see below), whose sum is σ = 31782976. Its totient is φ = 11918592.

The previous prime is 20857553. The next prime is 20857559. The reversal of 20857557 is 75575802.

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

It is not a de Polignac number, because 20857557 - 2² = 20857553 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 (20857553) 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 7 ways as a sum of consecutive naturals, for example, 496588 + ... + 496629.

It is an arithmetic number, because the mean of its divisors is an integer number (3972872).

Almost surely, 2^20857557 is an apocalyptic number.

It is an amenable number.

20857557 is a deficient number, since it is larger than the sum of its proper divisors (10925419).

20857557 is an equidigital number, since it uses as much as digits as its factorization.

20857557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 993227.

The product of its (nonzero) digits is 98000, while the sum is 39.

The square root of 20857557 is about 4567.0074447060. The cubic root of 20857557 is about 275.2672091474.

The spelling of 20857557 in words is "twenty million, eight hundred fifty-seven thousand, five hundred fifty-seven".