20857505 has 8 divisors (see below), whose sum is σ = 25064424. Its totient is φ = 16662400.

The previous prime is 20857483. The next prime is 20857511. The reversal of 20857505 is 50575802.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 16 + 20857489 = 4^2 + 4567^2 .

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

It is not a de Polignac number, because 20857505 - 2¹⁸ = 20595361 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 1565 + ... + 6645.

It is an arithmetic number, because the mean of its divisors is an integer number (3133053).

Almost surely, 2^20857505 is an apocalyptic number.

It is an amenable number.

20857505 is a deficient number, since it is larger than the sum of its proper divisors (4206919).

20857505 is an equidigital number, since it uses as much as digits as its factorization.

20857505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5907.

The product of its (nonzero) digits is 14000, while the sum is 32.

The square root of 20857505 is about 4567.0017516966. The cubic root of 20857505 is about 275.2669803909.

The spelling of 20857505 in words is "twenty million, eight hundred fifty-seven thousand, five hundred five".